ability to maintain physical distancing. For more discussion of this
subject, see the Need for Specific Provisions (Section V of the
preamble) on Ventilation.
    Transmission of SARS-CoV-2 is also possible via contact
transmission (both direct contact as well as surface contact), though
this risk is generally considered to be low compared to other forms of
transmission (CDC, April 5, 2021). Infectious droplets produced by an
infected person can land on and contaminate surfaces. Surface, or
indirect, transmission can then occur if another person touches the
contaminated surface and then touches their own mouth, nose, or eyes
(CDC, April 5, 2021). Contact transmission can also occur through
direct contact with someone who is infectious. In direct contact
transmission, the hands of a person who has COVID-19 can become
contaminated with the virus when the person touches their face, blows
their nose, coughs, or sneezes. The virus can then spread to another
person through direct contact such as a handshake or a hug.
    The risk posed by contact transmission depends on a number of
factors, including airflow and ventilation, as well as environmental
factors (e.g., heat, humidity), time between surface contamination and
a person touching those surfaces, the efficiency of transference of
virus particles, and the dose of virus needed to cause infection.
Studies show that the virus can remain viable on surfaces in
experimental conditions for hours to days, but that under typical
environment conditions 99% of the virus is no longer viable after three
days (Riddell et al., October 7, 2020; van Doremalen, April 16, 2020;
CDC, April 5, 2021). At this time, it is not clear what proportion of
SARS-CoV-2 infection are acquired through contact transmission and
infections can often be attributed to multiple transmission pathways.
    In recognition of the potential for contact transmission, CDC
recommends cleaning, hand hygiene, and, under certain circumstances,
disinfection for helping to prevent transmission of SARS-CoV-2 (CDC,
May 17, 2020; CDC, April 5, 2021). These are long established
recommendations to prevent the transmission of viruses that cause
respiratory illnesses (Siegel et al., 2007). The potential for contact
transmission was demonstrated in one study that reviewed cleaning and
disinfection in households (Wang et al., May 11, 2020). The study found
that the transmission of SARS-CoV-2 to family members was 77% lower
when chlorine- or ethanol-based disinfectants were used on a daily
basis compared to use only once in two or more days, irrespective of
other protective measures taken such as mask wearing and physical
distancing. For more discussion of this subject, see the Need for
Specific Provisions (Section V of the preamble) on Cleaning and
Disinfection.
    These methods of transmission are not mutually exclusive, and each
can present a risk to employees in healthcare settings. Based on these
methods of transmission, there are a number of factors--often present
in healthcare settings--that can increase the risk of transmission:
Indoor settings, prolonged exposure to respiratory particles, and lack
of proper ventilation (CDC, May 7, 2020). First, and most
significantly, healthcare employees in settings where patients with
suspected or confirmed COVID-19 receive treatment may be required to
have frequent close contact with infectious individuals, these settings
are typically not designed for physical distancing, and many areas in
these facilities are not ventilated for the purpose of minimizing
infectious diseases capable of droplet or airborne transmission.
Employees frequently touch shared surfaces and use shared items. Even
in healthcare settings where employees have their own offices or
equipment, they often share a number of common spaces with other
workers, including bathrooms, break rooms, and elevators. Based on
these characteristics, SARS-CoV-2 appears to be transmissible in
healthcare environments, a conclusion supported by existing data
(Howard, May 22, 2021). COVID-19 incidence rates have increased
significantly for adults of working age as the pandemic has progressed
in comparison with other age groups, with researchers noting that
occupational status might be a driver (Boehmer et al., September 23,
2020). Currently, case rates continue to be predominantly higher in
working age groups in comparison to children and those over the age of
65 (CDC, May 24, 2021).
    Given the high transmissibility expected in healthcare
environments, the exposure risk that employees face is high. This risk
is related to some extent to viral prevalence, which refers to the
number of individuals in healthcare settings who may be infectious at
any moment. As explained below, current data indicates that viral
prevalence in the population is based on a number of factors, including
the virus's existing reproductive number, the prevalence of pre-
symptomatic and asymptomatic transmission, and the recent documentation
of mutations of the virus that appear to be more infectious.
    The transmissibility of viruses is measured in part by their
reproductive number or ``R0.'' This number represents the average
number of subsequently-infected people (or secondary cases) that are
expected to occur from each existing case, which includes low
transmission events as well as super-spreading phenomenon. Thus, an R0
of ``1'' indicates that on average every one case of infection will

lead to one additional case. As long as a virus has an R0 of more than
1, it is expected to continue to spread throughout the population. The
observed R0 (also known as simply R) must be below 1 to prevent
sustained spread; such a reduction can be achieved through infection
control interventions (e.g., vaccination, non-pharmaceutical
interventions) that either reduce the susceptibility of the population
to the virus or reduce the likelihood of transmission within the
population (Delamater et al., 2019). During the early part of the
COVID-19 outbreak in China, before consistent protective measures were
put into place, the R0 for SARS-CoV-2 was estimated as 2.2 (Riou and
Althaus, January 30, 2020). Higher estimates of the R0 early in China
(5.7) have also been published (Sanche et al., April 7, 2020). R0
ranges from 2 to 5 have been published for earlier MERS and SARS-CoV-1
coronavirus outbreaks (WHO, May 2003; Choi et al., September 25, 2017).
Since the start of the COVID-19 pandemic, the R0 has varied depending
on the natural ebb and flow of rolling infection surges as well as the
fluctuating non-pharmaceutical interventions (NPIs) put in place, such
as face coverings, nonessential business shutdowns, and testing with
follow-up isolation and quarantining. The R0 value in the U.S. early in
the pandemic was estimated to be approximately 2 (Li et al., October
22, 2020), and this value has generally remained above 1 for the
country as a whole throughout the pandemic, with various states well
above and below this value at various times (Harvard Chan School of
Public Health, February 26, 2021; Shi et al., May 18, 2021).
    Pre-symptomatic and asymptomatic transmission are significant
drivers of the continued spread of COVID-19 (Johansson et al., January
7, 2021). Individuals are considered most infectious in the 48 hours
before experiencing symptoms and during the first few symptomatic days
(Cevik et al., October 23, 2020). The time it takes for a person to be
infected and then transmit the virus to another individual is called
the serial interval. Several studies have indicated that the serial
interval for COVID-19 is shorter than the time for symptoms to develop,
meaning that many individuals can transmit SARS-CoV-2 before they begin
to feel ill (Nishiura et al., March 4, 2020; Tindale et al., June 22,
2020). It is also possible for individuals to be infected and
subsequently transmit the virus without ever exhibiting symptoms. This
is called asymptomatic transmission. As noted earlier, a recent meta-
analysis reviewed 13 studies in which the asymptomatic prevalence
ranged from 4% to up to 41% (Byambasuren et al., December 11, 2020).
    The existence of both pre-symptomatic transmission and asymptomatic
infection and transmission pose serious challenges to containing the
spread of the virus. Although the risk of asymptomatic transmission is
42% lower than from symptomatic COVID-19 patients (Byambasuren et al.,
December 11, 2020), asymptomatic transmission may result in more
transmissions than symptomatic cases, perhaps because asymptomatic
persons are less likely to be aware of their infection and can
unknowingly continue to spread the disease to others. Similarly, pre-
symptomatic individuals can transmit the virus to others before they
know they are sick and should isolate, assuming they are aware of their
exposure. Existing evidence demonstrates that asymptomatic transmission
is a significant contributor to the spread of COVID-19 in the United
States. Johansson et al., (January 7, 2021) conducted a study to assess
the proportion of SARS-CoV-2 transmission from pre-symptomatic, never
symptomatic, and symptomatic individuals in the community. Based on
their modeling, they found 59% of transmission came from asymptomatic
transmission, including 35% from pre-symptomatic individuals and 24%
from individuals who never develop symptoms (Johansson et al., January
7, 2021).
    The SARS-CoV-2 virus also regularly mutates over time into
different genetic variants. Many of these variants results in no
increase in transmission or disease severity. However, the CDC monitors
for variants of interest, variants of concern, and variants of high
consequence (CDC, May 5, 2021). A variant of interest is one ``with
specific genetic markers that have been associated with changes to
receptor binding, reduced neutralization by antibodies generated
against previous infection or vaccination, reduced efficacy of
treatments, potential diagnostic impact, or predicted increase in
transmissibility or disease severity'' (CDC, May 5, 2021). CDC-listed
variants of interest include strains first identified in the United
States (e.g., B.1.526, B.1.526.1), the United Kingdom (e.g., B.1.525),
and Brazil (e.g., P.2). A variant of concern is one for which there is
``evidence of an increase in transmissibility, more severe disease
(e.g., increased hospitalizations or deaths), significant reduction in
neutralization by antibodies generated during previous infection or
vaccination, reduced effectiveness of treatments or vaccines, or
diagnostic detection failures'' (CDC, May 5, 2021). CDC-listed variants
of concern include strains first identified in the United States (e.g.,
B.1.427, B.1.429), United Kingdom (e.g., B.1.17), Brazil (e.g., P.1),
and South Africa (e.g., B.1.351). As of April 24, B.1.1.7 made up 60%
of infections in the United States (CDC, May 11, 2021). CDC notes that
B.1.1.7 is associated with a 50% increase in transmission, as well as
potentially increased incidence of hospitalizations and fatalities
(CDC, May 5, 2021). As new strains with increased transmissibility or
more severe effects enter the U.S. population, healthcare workers may
be among the first to be exposed to them when those who are infected
seek medical care (Howard, May 22, 2021).
    OSHA also recognizes that reported cases of SARS-CoV-2 likely
undercount actual infections in the U.S. population. This finding is
based on seroprevalence data, which measure the presence of specific
antibodies in the blood that are typically developed when an individual
is infected with SARS-CoV-2. Reported cases, in contrast, are based on
COVID-19 tests that measure active infections. Recent reported case
numbers suggest that approximately 10% of the US population has been
infected. However, only seven states reported seroprevalence below 10%
(i.e., Alaska, Hawaii, Maine, New Hampshire, Oregon, Vermont,
Washington) and 23 states plus Washington DC and Puerto Rico exceeded
20% (CDC, May 14, 2021). The likely reason for this difference is that
serological tests measure antibodies in the blood that can be detected
for a longer period of time than can an active COVID-19 infection. As
such, serological testing may be able to detect past COVID-19
infections in individuals who never sought out a viral test. A sampling
of states from the Nationwide Commercial Laboratory Seroprevalence
Survey illustrates this (CDC, May 14, 2021). On March 30, 2021,
California had reported 3,564,431 cases, but seroprevalence estimates
indicate that there have been 7,986,000 cases in the state (95% CI:
7,023,000-8,965,000). Similarly, Texas has reported 2,780,903 cases,
but seroprevalence data indicate 6,692,000 cases (95% CI: 5,624,000-
7,819,000). Given the very real possibility of higher numbers of cases
than are reported in national case counts, the disease burden discussed
in this document may well be underestimated.

References
Boehmer, TK et al., (2020, September 23). Changing Age Distribution
of the COVID-19 Pandemic--United States, May-August 2020. MMWR Morb
Mortal Wkly Rep 2020; 69: 1404-1409. DOI: http://dx.doi.org/10.15585/mmwr.mm6939e1external. (Boehmer et al., September 23,
2020).
Brlek, A et al., (2020, June 16). Possible indirect transmission of
COVID-19 at a squash court, Slovenia, March 2020: case report. Epi
Inf 148: 1-3. (Brlek et al., June 16, 2020).
Bulfone, TC et al., (2020, November 29). Outdoor Transmission of
SARS-CoV-2 and Other Respiratory Viruses: A Systematic Review.
(2020). The Journal of Infectious Diseases 223: 550-561, https://doi.org/10.1093/infdis/jiaa742. (Bulfone et al., November 29, 2020).
Byambasuren, O et al., (2020, December 11). Estimating the extent of
asymptomatic COVID-19 and its potential for community transmission:
Systematic review and meta-analysis. Official Journal of the
Association of Medical Microbiology and Infectious Disease Canada.
5(4): 223-234 doi: 10.3138/jammi-2020-0030. (Byambasuren et al.,
December 11, 2020).
Centers for Disease Control and Prevention (CDC). (2020, March 12).
What healthcare personnel should know about caring for patients with
confirmed or possible coronavirus disease 2019 (COVID-19). https://www.cdc.gov/coronavirus/2019-ncov/hcp/caring-for-patients-H.pdf.
(CDC, March 12, 2020).
Centers for Disease Control and Prevention (CDC). (2020, May 17).
Hand hygiene recommendations: Guidance for healthcare providers
about hand hygiene and COVID-19. https://www.cdc.gov/coronavirus/2019-ncov/hcp/hand-hygiene.html. (CDC, May 17, 2020).
Centers for Disease Control and Prevention (CDC). (2021, February
23). Interim Infection Prevention and Control Recommendations for
Healthcare Personnel During the Coronavirus Disease 2019 (COVID-19)
Pandemic. https://www.cdc.gov/coronavirus/2019-ncov/hcp/infection-control-recommendations.html. (CDC, February 23, 2021).
Centers for Disease Control and Prevention (CDC). (2021, April 5).
Science Brief: SARS-CoV-2 and Surface (Fomite) Transmission for
Indoor Community Environments. https://www.cdc.gov/coronavirus/2019-ncov/more/science-and-research/surface-transmission.html. (CDC,
April 5, 2021).
Centers for Disease Control and Prevention (CDC). (2021, May 5).
SARS-CoV-2 Variant Classifications and Definitions. https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/variant-surveillance/variant-info.html. (CDC, May 5, 2021).
Centers for Disease Control and Prevention (CDC). (2021, May 7).
Scientific Brief: SARS-CoV-2 Transmission. https://www.cdc.gov/coronavirus/2019-ncov/science/science-briefs/sars-cov-2-transmission.html. (CDC, May 7, 2021).
Centers for Disease Control and Prevention (CDC). (2021, May 14)
Nationwide Commercial Laboratory Seroprevalence Survey. https://covid.cdc.gov/covid-data-tracker/#national-lab. (CDC, May 14, 2021).
Centers for Disease Control and Prevention (CDC). (2021, May 24).
Demographic Trends of COVID-19 cases and deaths in the US reported
to CDC: Cases by age group. https://covid.cdc.gov/covid-data-tracker/#demographics. (CDC, May 24, 2021).
Census Bureau. (2020, June 25). Annual Estimates of the Resident
Population for Selected Age Groups by Sex for the United States:
April 2010 to July 1, 2019. https://www2.census.gov/programs-surveys/popest/tables/2010-2019/national/asrh/nc-est2019-agesex.xlsx. (Census Bureau, June 25, 2020).
Cevik, M et al., (2020, October 23) Virology, transmission, and
pathogenesis of SARS-CoV-2 BMJ 2020; 371: m3862 doi: https://doi.org/10.1136/bmj.m3862. (Cevik et al., October 23, 2020).
Choi, S et al., (2017, September 25). High reproduction number of
Middle East respiratory syndrome coronavirus in nosocomial
outbreaks: Mathematical modelling in Saudi Arabia and South Korea. J
Hos Inf 99: 162-168. (Choi et al., September 25, 2017).
Chu, DK et al., (2020, June 27). Physical Distancing, Face Masks,
and Eye Protection to Prevent Person-to-Person Transmission of SARS-
CoV-2 and COVID-19: A systematic review and meta-analysis. Lancet
395: 1973-1987. (Chu et al., June 27, 2020).
Cummings et al., (2020, July 9). Risk factors for healthcare
personnel infection with endemic coronaviruses (HKU1, OC43, NL63,
229E): Results from the respiratory protection effectiveness
clinical trial (REPECT). Clin Infect Dis doi: 10.1093/cid/ciaa900.
(Cummings et al., July 9, 2020).
Delamater, PL et al., (2019). Complexity of the basic reproduction
number (R0). Emerging Infectious Disease 25(1): 1-4. https://doi.org/10.3201/eid2501.171901. (Delamater et al., 2019).
Doung-ngern, P et al., (2020, September 14). Case-control Study of
Use of Personal Protective Measures and Risk for SARS Coronavirus 2
Infection, Thailand. Emerg In Dis 26, 11: 2607-2616. (Doung-ngern et
al., September 14, 2020).
Fennelly, K. (2020, July 24). Particle sizes of infectious aerosols:
Implications for infection control. Lancet Respir Med 2020; 8: 914-
24. https://doi.org/10.1016/S2213-2600(20)30323-4. (Fennelly, July
24, 2020).
Gunther, T et al., (2020, October 27). SARS-CoV-2 outbreak
investigation in a German meat processing plant. EMBO Mol Med (2020)
12: .e13296. doi.org/10.15252/emmm.202013296. (Gunther et al.,
October 27, 2020).
Harding, H, Broom, A, Broom, J. (2020, June 1). Aerosol-generating
procedures and infective risk to healthcare workers from SARS-CoV-2:
the limits of the evidence. J Hosp Infect. 2020; 105(4): 717-725.
doi: 10.1016/j.jhin.2020.05.037. (Harding et al., June 1, 2020).
Harvard Chan School of Public Health. (2020, February 26).
Visualizing COVID-19's Effective Reproduction Number (Rt). http://metrics.covid19-analysis.org/. (Harvard Chan School of Public
Health, February 26, 2020).
Heinzerling, A et al., (2020, April 17). Transmission of COVID-19 to
Health Care Personnel During Exposures to a Hospitalized Patient--
Solano County, California, February 2020. MMWR Morb Mortal Wkly Rep
2020; 69: 472-476. DOI: http://dx.doi.org/10.15585/mmwr.mm6915e5.
(Heinzerling et al., April 17, 2020).
Honein, MA, Christie, A, Rose, DA et al., (2020, December 11).
Summary of Guidance for Public Health Strategies to Address High
Levels of Community Transmission of SARS-CoV-2 and Related Deaths,
December 2020. MMWR Morb Mortal Wkly Rep 2020; 69: 1860-1867. DOI:
http://dx.doi.org/10.15585/mmwr.mm6949e2. (Honein et al., December
11, 2020).
Howard, J. (2021, May 22). ``Response to request for an assessment
by the National Institute for Occupational Safety and Health,
Centers for Disease Control and Prevention, U.S. Department of
Health and Human Services, of the current hazards facing healthcare
workers from Coronavirus Disease-2019 (COVID-19).'' (Howard, May 22,
2021).
Johansson, MA et al., (2021, January 7). SARS-CoV-2 transmission
from people without COVID-19 symptoms. JAMA Network Open. 4(1):
e2035057. doi: 10.1001/jamanetworkopen.2020.35057. (Johansson et
al., January 7, 2021).
Klompas, M et al., (2021, February 9). A SARS-CoV-2 Cluster in an
Acute Care Hospital. Annals of Internal Medicine [Epub ahead of
print 9 February 2021]. doi:10.7326/M20-7567. (Klompas et al.,
February 9, 2021).
Kwon, KS et al., (2020, November 23). Evidence of Long-Distance
Droplet Transmission of SARS-CoV-2 by Direct Air Flow in a
Restaurant in Korea. J Korean Med Sci 35(46): e415. (Kwon et al.,
November 23, 2020).
Lednicky, JA et al., (2020, September 11). Viable SARS-CoV-2 in the
air of a hospital room with COVID-19 patients. Int J Infect Dis 100:
476-482. (Lednicky et al., September 11, 2020).
Leong, YC et al., (2020, December). Clinical considerations for out-
of-hospital cardiac arrest management during COVID-19. Resuscitation
Plus.<PHONE_NUMBER>27. https://doi.org/10.1016/j.resplu.2020.100027.
(Leong et al., December 2020).
Li, Y et al., (2020, October 22).The temporal association of
introducing and lifting non-pharmaceutical interventions with the
time varying reproduction number (R) of SARS-CoV-2: A modeling study
across 131 countries. Lancet Infect Dis 21: 193-202. (Li et al.,
October 22, 2020).
Li, H et al., (2020, November 3). Dispersion of Evaporating Cough
Droplets in Tropical Outdoor Environment. Phys

Fluids 32, 113301. https://doi.org/10.1063/5.0026360. (Li et al.,
November 3, 2020).
Nishiura, H et al., (2020, March 4). Serial interval of novel
coronavirus (COVID-19) infections. Int J Infect Dis. 2020 Apr; 93:
284-286. doi: 10.1016/j.ijid.2020.02.060. Epub 2020 Mar 4. PMID:
32145466; PMCID: PMC7128842. (Nishiura et al., March 4, 2020).
Nolte, KB et al., (2020, December 14). Design and Construction of a
Biosafety Level-3 Autopsy Laboratory. Arch Path Lab Med. doi:
10.5858/arpa.2020-0644-SA. (Nolte et al., December 14, 2020).
Payne, D and Peache, M. (2021, February 4). Aerosol-generating
procedures in home care. Br J Community Nurs. 26 (2): 76-80. https://dx.doi.org/10.12968/bjcn.2<IP_ADDRESS>. (Payne and Peache, February
4, 2021).
Pluim, JME et al., (2018, June 6). Aerosol production during
autopsies: the risk of sawing in bone. Forensic Science
International 289: 260-267. https://doi.org/10.1016/j.forsciint.2018.05.046. (Pluim et al., June 6, 2018).
Riddell, S et al., (2020, October 7). The effect of temperature on
persistence of SARS-CoV-2 on common surfaces. Virol J 17:145 DOI:
https://doi.org/10.1186/s12985-020-01418-7. (Riddell et al., October
7, 2020).
Riou, J and Althaus, CL. (2020, January 30). Pattern of early human-
to-human transmission of Wuhan 2019 novel coronavirus (2019-nCoV),
December 2019 to January 2020. Eurosurveillance 25(4): pii=2000058.
https://doi.org/10.2807/1560-7917.ES.2<IP_ADDRESS>0058. (Riou and
Althaus, January 30, 2020).
Sagami, R et al., (2021, January). Aerosols Produced by Upper
Gastrointestinal Endoscopy: A Quantitative Evaluation. The American
journal of gastroenterology. 116 (1): 202-205. https://doi.org/10.14309/ajg.0000000000000983. (Sagami et al., January 2021).
Sanche, S et al., (2020, April 7). High contagiousness and rapid
spread of severe acute respiratory syndrome coronavirus 2. Emerg Inf
Dis 26(7): 1470-1477. (Sanche, April 7, 2020).
Schoen, LJ. (2020, May). Guidance for building operations during the
COVID-19 pandemic. ASHRAE Journal 72-72. https://www.ashrae.org/file%20library/technical%20resources/ashrae%20journal/2020journaldocuments/72-74_ieq_schoen.pdf. (Schoen, May 2020).
Shi, A et al., (2021, May 18). COVID-19 Spread Mapper: Table of
metrics for May 18, 2021. http://metrics.covid19-analysis.org/?_inputs_↦_metric=%22rt%22&compare_sel_countries=null&show_ci=%22No%22&Rt_table_search=%22%22↦_date=%222021-05-18%22&compare_metric=%5B%22rt%22%2C%22case_rate%22%2C%22death_rate%22%5D&compare_submit=0&table_select_resolution=%22subnat_USA%22&table_date=%222021-05-18%22&select_resolution=%22auto%22&compare_sel_states=null&compare_sel_counties=null. (Shi et al., May 18, 2021).
Siegel, JD, Rhinehart, E, Jackson, M, Chiarello, L, and the
Healthcare Infection Control Practices Advisory Committee. (2007).
2007 Guideline for Isolation Precautions: Preventing Transmission of
Infectious Agents in Healthcare Settings. Centers for Disease
Control and Prevention. https://www.cdc.gov/infectioncontrol/guidelines/isolation/index.html. (Siegel et al., 2007)
Teng, M et al., (2020, September 16) Endoscopy during COVID-19
pandemic: An overview of infection control measures and practical
application. World J Gastrointest Endosc. 12 (9): 256-265. https://dx.doi.org/10.4253/wjge.v12.i9.256. (Teng et al, September 16,
2020).
Tindale, LC et al., (2020, June 22). Evidence for transmission of
COVID-19 prior to symptom onset. Elife. 2020; 9: e57149. Published
2020 Jun 22. doi: 10.7554/eLife.57149. (Tindale et al., June 22,
2020).
Tran, K et al., (2012, April 26). Aerosol generating procedures and
risk of transmission of acute respiratory infections to healthcare
care: A systematic review. PLOSONE 7(4): e35797. doi: 10.1371/
journal.pone.0035797. (Tran et al., April 26, 2012).
van Doremalen, N et al., (2020, April 16). Aerosol and Surface
Stability of SARS-CoV-2 as Compared with SARS-CoV-1. N Engl J Med.
2020 Apr 16; 382(16): 1564-1567. doi: 10.1056/NEJMc2004973. (van
Doremalen et al., April 16, 2020).
Wang, Y et al., (2020, May 11). Reduction of secondary transmission
of SARS-CoV-2 in households by face mask use, disinfection and
social distancing: A cohort study in Beijing, China. BMJ Glob
Health. 2020; 5(5): e002794. doi: 10.1136/bmjgh-2020-002794. (Wang
et al., May 11, 2020).
World Health Organization (WHO). (2003, May). Consensus document on
the epidemiology of severe acute respiratory syndrome (SARS). WHO/
CDS/CSR/GAR/2003.11. https://apps.who.int/iris/bitstream/handle/10665/70863/WHO_CDS_CSR_GAR_2003.11_eng.pdf?sequence=1&isAllowed=y.
(WHO, May 2003)
c. The Effect of Vaccines on the Grave Danger Presented by SARS-CoV-2
    The development of safe and highly effective vaccines and the on-
going nation-wide distribution of these vaccines are encouraging
milestones in the nation's response to COVID-19. Although there was
initial uncertainty attached to the performance of authorized vaccines
outside of clinical trials, vaccines have been in use for several
months and they have proven effective in reducing transmission as well
as the severity of COVID-19 cases. Data now available clearly establish
that fully-vaccinated persons (defined as two weeks after the second
dose of the mRNA vaccines or two weeks after the single dose vaccine)
have a greatly reduced risk compared to unvaccinated individuals. This
includes reductions in deaths, severe infections requiring
hospitalization, and less severe symptomatic infections. The
combination of data from clinical trials and data from mass vaccination
efforts points increasingly to a significantly lower risk in settings
where all workers are fully vaccinated and are not providing direct
care for individuals with suspected or confirmed COVID-19. OSHA has
therefore determined that there is insufficient evidence in the record
to support a grave danger finding for employees in non-healthcare
workplaces (or discrete segments of workplaces) where all employees are
vaccinated. However, in healthcare settings where workers are
vaccinated, as discussed below, the best available evidence establishes
a grave danger still exists, given the greater potential for
breakthrough cases in light of the greater frequency of exposure to
suspected and confirmed COVID-19 patients in those settings (Birhane et
al., May 28, 2021). In addition, the best available evidence shows that
vaccination has not eliminated the grave danger in mixed healthcare
workplaces (i.e., those where some workers are fully vaccinated and
some are unvaccinated) or in those healthcare workplaces where no one
has yet been vaccinated.
The Effectiveness of Authorized Vaccines
    There are currently three vaccines for the prevention of COVID-19
that have received EUAs from the FDA, allowing for their distribution
in the U.S.: The Pfizer-BioNTech COVID-19 vaccine, the Moderna COVID-19
vaccine, and the Janssen COVID-19 vaccine. Pfizer-BioNTech and Moderna
are mRNA vaccines that require two doses administered three weeks and
one month apart, respectively. Janssen is a viral vector vaccine that
requires a single dose (CDC, April 2, 2021). The vaccines were shown to
greatly exceed minimum efficacy standards in preventing COVID-19 in
clinical trial participants (FDA, December 11, 2020; FDA, December 18,
2020; FDA, February 26, 2021). Data from clinical trials for all three
vaccines and observational studies for the two mRNA vaccines clearly
establish that fully vaccinated persons have a greatly reduced risk of
SARS-CoV-2 infection compared to unvaccinated individuals. This
includes severe infections

requiring hospitalization and those resulting in death, as well as less
severe symptomatic infections.
    As stated above, the three authorized vaccine were shown to be
highly efficacious in clinical trials. Clinical trial results are
commonly considered a best case scenario (e.g., conducted in relatively
young and healthy populations), while evidence from follow-up
observational studies provides insight on a more diverse population.
This essential data from observational studies in populations who were
vaccinated outside of clinical trials is emerging and shows that the
mRNA vaccines are highly effective. At this time, observational studies
for the single dose, viral vector vaccine are not available. Some of
the studies for mRNA vaccines examined high-risk populations, such as
healthcare workers. Thus, the degree of protection in these studies can
be extrapolated to a wide range of workplace settings in healthcare.
The results from these studies are very encouraging.
    A study of 3,950 health care personnel, first responders, and other
essential workers who completed weekly SARS-CoV-2 testing for 13
consecutive weeks reported 90% effectiveness (95% confidence interval
[CI] = 68%-97%) after full vaccination with either mRNA vaccine
(Thompson et al., April 2, 2021). Still, 22.9% of PCR-confirmed
infections required medical care; these included two hospitalizations
but no deaths. A study of more than 8,000 individuals in the U.S.
general population found that two doses of either mRNA vaccine were
88.7% effective in preventing SARS-CoV-2 infection (Pawlowski et al.,
February 27, 2021). Similar to the above results in essential workers,
although breakthrough infection occurred, vaccinated patients in this
study who were subsequently diagnosed with COVID-19 had significantly
lower 14-day hospital admission rates than matched unvaccinated
participants (3.7% vs. 9.2%). Hall et al., (April 23, 2021), in a study
of U.K. healthcare workers with bi-weekly testing, documented an 85%
effectiveness of the Pfizer-BioNTech vaccine, though those authors
required only one week after dose two for classification as fully
vaccinated. Research from Israel provides additional evidence of high
effectiveness for the Pfizer-BioNTech vaccine (Dagan et al., February
24, 2021).
    Data available regarding vaccine efficacy against some SARS-CoV-2
variants of concern illustrate that the vaccines remain effective at
reducing symptomatic infections. Two doses of the Pfizer-BioNTech
COVID-19 vaccine was highly effective (85-86%) against SARS-CoV-2
infection and symptomatic COVID-19 during a period when B.1.1.7 was the
predominant circulating strain in the UK (Hall et al., April 23, 2021).
In Israel, the Pfizer-BioNTech vaccine was 92% effective even with the
proportion of cases due to the B.1.1.7 becoming the dominant virus in
circulation towards the end of the evaluation period (Dagan et al.,
February 24, 2021). Another study testing the Pfizer-BioNTech COVID-19
vaccine found that it was equally capable of neutralizing the notable
variants from the United Kingdom and South Africa (Xie et al., February
8, 2021). This finding was then reflected in a Qatari study that found
that the Pfizer-BioNTech vaccine was not only effective at preventing
disease in people infected by those variants, but was observed as 100%
effective in preventing fatalities from COVID-19 (Abu-Raddad et al.,
May 5, 2021). The Janssen vaccine clinical trial was conducted during a
time in which SARS-CoV-2 variants were circulating in South Africa
(B.1.351 variant) and Brazil (P.2 variant). At 28 or more days past
vaccination, efficacy against moderate to severe/critical disease was
72% in the United States; 68% in Brazil; 64% in South Africa (FDA,
February 26, 2021). Although some studies have reported antibodies to
be less effective against the B.1.351 variant, antibody activity in
serum from vaccinated persons was generally higher than activity from
serum of persons who recovered from COVID-19 (CDC, April 2, 2021).
    A major question not fully addressed in the original clinical
trials is whether vaccinated individuals can become infected and shed
virus, even if they are asymptomatic. Thompson et al., (April 2, 2021),
reported that 11% of the PCR-confirmed breakthrough infections in their
essential worker population were asymptomatic, indicating a concern for
asymptomatic transmission. However, this concern is based on studies
indicating asymptomatic transmission among unvaccinated individuals and
it is not known if this phenomena occurs in infected vaccinated
individuals. In the Moderna clinical trial, reverse transcription
polymerase chain reaction (RT-PCR) testing was performed on
participants at their second vaccination visit; asymptomatic positives
in the vaccinated group were less than half those in the placebo group
(Baden et al., December 30, 2020, supplemental files Table s18). In a
Mayo clinic study, an 80% reduction in risk of positive pre-procedural
screening tests was observed in patients tested after their second
vaccine dose (Tande et al., March 10, 2021). A study of more than
140,000 healthcare workers and their almost 200,000 household members
reported a 30% reduction in risk of documented COVID-19 cases in the
household members after the healthcare provider was fully vaccinated
(Shah et al., March 21, 2021). In the Israeli general population, the
estimated vaccine effectiveness for the asymptomatic infection proxy
group (infection without documented symptoms, which could have included
undocumented mild symptoms) was 90% at 7 or more days after the second
dose (Dagan et al., February 24, 2021). Preliminary data from Israel
suggest that people vaccinated with the Pfizer-BioNTech COVID-19
vaccine who develop COVID-19 have a four-fold lower viral load than
unvaccinated people (Levine-Tiefenbrun, February 8, 2021). As noted by
CDC (April 2, 2021), this observation may indicate reduced
transmissibility, because viral load is thought to be a major factor in
transmission (Marks et al., February 2, 2021).
    The CDC has acknowledged that a ``growing body of evidence suggests
that fully vaccinated people are less likely to have asymptomatic
infection or transmit SARS-CoV-2 to others'' (CDC, April 2, 2021). The
decreased risk for infection, especially serious infection, combined
with decreased risk of transmission to others has allowed the CDC to
relax some recommendations for individuals who are in community or
public settings and who are fully vaccinated with one of the three FDA
authorized vaccines, as follows.
     Quarantine is no longer required for fully vaccinated
individuals who remain asymptomatic following exposure to a COVID-19
infected person (CDC, May 13, 2021).
     Testing following a known exposure is no longer needed for
a fully vaccinated person, as long as the individual remains
asymptomatic and is not in specific settings such as healthcare (CDC,
April 27, 2021a), non-healthcare congregate facilities (e.g.,
correctional and detention facilities, homeless shelters) or high-
density workplaces (e.g., poultry processing plants) (CDC, May 13,
2021).
    In non-healthcare settings, fully vaccinated people no longer need
to wear a mask or physically distance, except where required by
federal, state, local, tribal, or territorial laws, rules, and
regulations, including local business and workplace guidance (CDC, May
13, 2021). In healthcare settings, the picture is more mixed. While the

CDC still recommends source controls for vaccinated healthcare workers
to protect unvaccinated people, it has relaxed several NPIs for health
care providers (HCP) in some circumstances. CDC has stated that ``fully
vaccinated HCP could dine and socialize together in break rooms and
conduct in-person meetings without source control or physical
distancing'' (CDC, April 27, 2021a). The CDC also recommends that fully
vaccinated HCP no longer need to be restricted from work after a high-
risk exposure, as long as they remain symptom-free (CDC, April 27,
2021a). Perhaps more significantly, while acknowledging the growing
body of evidence against SARS-CoV-2 transmission from vaccinated people
to unvaccinated people, the CDC has not identified evidence of a
substantial risk of such transmission even in healthcare settings.
Therefore, pending additional evidence of such transmission, the risk
of transmission from vaccinated healthcare workers to unvaccinated co-
workers does not appear to be high enough to warrant OSHA's imposition
of mandatory controls through an ETS to protect unvaccinated workers
from exposure to vaccinated workers.
    On the other hand, HCP treating suspected and confirmed COVID-19
patients are expected to have higher exposures to the SARS-CoV-2 virus
than others in the workforce, because such work involves repeated
instances of close contact with infected patients (Howard, May 22,
2021). Exposure can be even higher in aerosol generating activities.
Indeed, one study reported higher infection rates among vaccinated HCWs
during a regional COVID-19 surge (Keehner et al., Mar. 23, 2021). Thus,
the CDC has not relaxed infection control practices or PPE intended to
protect HCP, including respirator use. (CDC, April 27, 2021a). NIOSH
has stated that the ``available evidence shows that healthcare workers
are continuing to become infected with SARS-CoV-2 . . . including both
vaccinated and unvaccinated workers, and the conditions for the
transmission of the virus exist at healthcare workplaces'' (Howard, May
22, 2021). The CDC has also indicated that it will continue ``to
evaluate the impact of vaccination; the duration of protection,
including in older adults; and the emergence of novel SARS-CoV-2
variants on healthcare infection prevention and control
recommendations'' (CDC, April 27, 2021a). OSHA, too, will continue to
monitor this issue and revise the ETS as appropriate.
Grave Danger Exists in Healthcare Workplaces Where Unvaccinated Workers
Are Present
    The evidence shows that the advent of vaccines does not eliminate
the grave danger from exposure to SARS-CoV-2 in healthcare workplaces
where less than 100% of the workforce is fully vaccinated. Unvaccinated
workers can transmit the virus to each other and can become infected as
a result of exposure to persons with COVID-19 who enter the healthcare
facility. An outbreak of COVID-19 due to an unvaccinated, symptomatic
HCP was recently reported in a skilled nursing facility in which 90.4%
of residents had been vaccinated (Cavanaugh, April 30, 2021). The
outbreak, due to the R.1 variant, caused attack rates that were three
to four times higher in unvaccinated residents and HCPs as among those
who were vaccinated. Additionally, unvaccinated persons were
significantly more likely to experience symptoms or require
hospitalization. Therefore, unvaccinated employees at these workplaces
remain at grave danger of infection, along with the serious health
consequences of COVID-19, as discussed in the remainder of this
section.
    Although the risk appears to be lower, breakthrough infections of
vaccinated individuals do occur, but the potential for secondary
transmission remains not fully substantiated. For instance, a small yet
significant portion of the population does not respond well to
vaccinations (Agha et al., April 7, 2021; Boyarsky et al., May 5, 2021;
Deepak et al., April 9, 2021; ACI, April 28, 2021) and may be as
vulnerable as unvaccinated individuals. These individuals could
potentially transmit the SARS-CoV-2 infection to unvaccinated
employees. In a California study, seven out of 4,167 fully vaccinated
health care workers experienced breakthrough infections (Keehner et
al., May 6, 2021). A similar study from the Mayo Clinic, included
44,011 fully vaccinated individuals with 30 breakthrough infections
being recorded (Swift et al., April 26, 2021). Of those breakthrough
cases, 73% were symptomatic. Secondary transmission was not evaluated
in the study. A nursing facility in Chicago found 22 possible
breakthrough cases of SARS-COV-2 infection among fully vaccinated staff
and residents (Teran et al., April 30, 2021). Of those cases, 36% were
symptomatic. However, no secondary transmission was observed in the
facility. The lack of secondary transmission was likely due to the
facility's implementation of non-pharmaceutical interventions and high
vaccination rates. The authors concluded that to ensure outbreaks do
not occur from breakthrough infections in workplaces with vaccinated
and unvaccinated workers that the facilities need to maintain high
vaccine coverage and non-pharmaceutical interventions. While these
breakthrough events appear to be uncommon, it is important to remember
how quickly a few cases can result in an outbreak in unvaccinated
populations.
    Moreover, even though the U.S. is approaching the time where there
is sufficient vaccine supply for the entire U.S. population,
administering the vaccine throughout the country will still take more
time. As of May 24, 2021, CDC statistics show that 43% of the
population between 18 and 65 has been fully vaccinated (CDC, May 24,
2021a). To this end, there is still a need to strengthen confidence in
the safety and effectiveness of the vaccines for significant portions
of the population, including workers, to reduce vaccine hesitancy. Even
in the healthcare industry, where distribution has enabled entire
worker populations to be completely vaccinated by now, some workers
exhibited reluctance to getting vaccinated. On January 4, 2021, a study
of 1,398 U.S. emergency department health care personnel found that 95%
were offered the vaccine, with 14% declining (Schrading et al.,
February 19, 2021). In February of 2021, the CDC released a study of
initial vaccine efforts at skilled nursing facilities offering long-
term care (Gharpure et al., February 5, 2021). The study found that
only 37.5% of eligible staff were vaccinated, leaving a potentially
significant population vulnerable to SARS-CoV-2 infections and capable
of transmission.
    An anonymous survey of employees across the Yale Medicine and Yale
New Haven Health system was used to estimate the prevalence of and
underlying reasons for COVID-19 vaccine hesitancy. The survey was sent
to about 33,000 employees and medical staff across the Yale healthcare
system and included clinical staff and those who support the critical
infrastructure without direct patient contact (e.g., food service
staff). Out of 3,523 responses (an 11% response rate), 85% of
respondents stated they were ``extremely likely'' or ``somewhat
likely'' to receive the COVID-19 vaccine. Of that 85%, 12% expressed
mild hesitancy by stating they would get it within the next 6 months.
But 14.7% of overall respondents expressed reluctance by responding
``neither likely nor unlikely,'' ``somewhat unlikely,'' or ``extremely
unlikely'' to receive the COVID-19 vaccine. Overall, 1 in 6 personnel
in this health system survey expressed at least

some reluctance to get vaccinated (Roy et al., December 29, 2020).
    Findings in more recent surveys of the general working population
from 18 to 65 years old show similar rates of people who stated they
would not, probably would not, or would only if required get vaccinated
(18.2%) (Census Bureau, May 5, 2021); 17-26% (KFF, April 22, 2021). In
March 2021, a survey found that healthcare employees reported some of
the highest vaccination percentages of any sector (78.3% and 67.7%,
respectively; King et al., April 24, 2021). However, future growth of
vaccination may be a concern with vaccine hesitation in those sectors
reported as 14.1% and 15.9%, respectively.
    That unvaccinated healthcare workers remain in grave danger is
emphasized by the fact that thousands of new hospital admissions still
occur each day (CDC, May 24, 2021b) in the midst of significant
distribution of over three hundred million effective vaccine doses.
These factors indicate that transmission remains robust and significant
portions of the population remain vulnerable to COVID-19. Spread of the
disease within the healthcare workforce may start with a worker
becoming ill through community transmission or an ill patient seeking
treatment. The rate of new cases, hospitalizations, and deaths peaked
in January 2021, just before vaccines became more widely available
outside of healthcare settings. The January to February decline,
however, is likely not attributable in large part to the new vaccines
alone, because only a small portion of the population had received
them. During this time, variants of concern, such as B.1.1.7, that are
more transmissible and may result in worse health outcomes, have become
the majority source of infection (CDC, May 24, 2021c). Hundreds of
people each day are still dying of COVID-19 in early May 2021, many of
them working-age adults (May 24, 2021d).
    OSHA will continue to monitor trends as more of the population
becomes vaccinated and the post-vaccine evidence base continues to
grow. If and when OSHA finds a grave danger from the virus no longer
exists for covered healthcare workplaces (or some portion thereof), or
new information necessitates a change in measures necessary to address
the grave danger, OSHA will update the rule as appropriate.
    In summary, the availability and use of safe and effective vaccines
for COVID-19 is a critical milestone that has led to a marked decrease
in risk for healthcare employees generally, but grave danger still
remains for those whose jobs require them to work in settings where
patients with suspected or confirmed COVID-19 receive care. CDC has
determined that the remaining risk for fully vaccinated persons outside
of healthcare settings is low enough to justify foregoing other layers
of controls for settings where all persons are fully vaccinated and
asymptomatic (CDC, April 27, 2021), but the CDC continues to recommend
respirators and PPE for fully vaccinated healthcare employees in
settings where patients with suspected or confirmed COVID-19 receive
care. Based on CDC guidance and the best available evidence, OSHA finds
a grave danger in healthcare for vaccinated and unvaccinated HCP
involved in the treatment of COVID-19 patients.
References
Abu-Raddad, LJ et al., (2021, May 5). Effectiveness of the BNT162b2
Covid-19 Vaccine against the B.1.1.7 and B.1.351 Variants. NEJM DOI:
10.1056/NEJMc2104974 (Abu-Raddad et al., May 5, 2021).
Agency for Clinical Innovation (ACI). (2021, April 28). Evidence
check: Immunocompromised patients and COVID-19 vaccines. https://aci.health.nsw.gov.au/__data/assets/pdf_file/0009/645750/Evidence-check-Immunocompromised-patients-COVID-19-vaccines.pdf. (ACI, April
28, 2021).
Agha et al., (2021, April 7). Suboptimal response to COVID-19 mRNA
vaccines in hematologic malignancies patients. medRxiv
2<IP_ADDRESS>54949. https://doi.org/10.1101/2<IP_ADDRESS>54949.
(Agha, et al., April 7, 2021).
Baden, L et al., (2021, December 30). Efficacy and safety of the
mRNA-1273 SARS-CoV-2 Vaccine. The New England Journal of Medicine,
384(5), 403-416. https://doi.org/10.1056/NEJMoa2035389. (Baden et
al., December 30, 2020).
Birhane, M et al., (2021, May 28). COVID-19 Vaccine Breakthrough
Infections Reported to CDC--United States, January 1-April 30, 2021.
MMWR 70: 792-793. http://dx.doi.org/10.15585/mmwr.mm7021e3. (Birhane
et al., May 28, 2021).
Boyarsky, BJ et al., (2021, May 5). Antibody Response to 2-Dose
SARS-CoV-2 mRNA Vaccine Series in Solid Organ Transplant Recipients.
JAMA. 2021 May 5. doi: 10.1001/jama.2021.7489. PMID: 33950155.
(Boyarsky et al., May 5, 2021).
Cavanaugh, AM et al., (2021, April 30). COVID-19 outbreak associated
with a SARS-CoV-2 R.1 lineage variant in a skilled nursing facility
after vaccination program--Kentucky, March 2021. MMWR 70: 639-643.
http://dx.doi.org/10.15585/mmwr.mm7017e2. (Cavanaugh et al., April
30, 2021).
Census Bureau. (2021, May 5). Household Pulse Survey COVID-19
Vaccination Tracker. https://www.census.gov/library/visualizations/interactive/household-pulse-survey-covid-19-vaccination-tracker.html. (Census Bureau, May 5, 2021).
Centers for Disease Control and Prevention (CDC). (2021, April 2).
Science brief: Background rationale and evidence for public health
recommendations for fully vaccinated people. https://www.cdc.gov/coronavirus/2019-ncov/science/science-briefs/fully-vaccinated-people.html. (CDC, April 2, 2021).
Centers for Disease Control and Prevention (CDC). (2021a, April 27).
Updated healthcare infection prevention and control recommendation
in response to COVID-19 vaccination. https://www.cdc.gov/coronavirus/2019-ncov/hcp/infection-control-after-vaccination.html.
(CDC, April 27, 2021a).
Centers for Disease Control and Prevention (CDC). (2021b, April 27).
Domestic travel during COVID-19. https://www.cdc.gov/coronavirus/2019-ncov/travelers/travel-during-covid19.html. (CDC, April 27,
2021b).
Centers for Disease Control and Prevention (CDC). (2021, May 13).
Interim public health recommendations for fully vaccinated people.
https://www.cdc.gov/coronavirus/2019-ncov/vaccines/fully-vaccinated-guidance.html. (CDC, May 13, 2021).
Centers for Disease Control and Prevention (CDC). (2021a, May 24).
Demographic Trends of People Receiving COVID-19 Vaccinations in the
United States. https://covid.cdc.gov/covid-data-tracker/?CDC_AA_refVal=https%3A%2F%2Fwww.cdc.gov%2Fcoronavirus%2F2019-ncov%2Fcases-updates%2Fcas%E2%80%A6#vaccination-demographic. (CDC,
May 24, 2021a).
Centers for Disease Control and Prevention (CDC). (2021b, May 24).
COVID data tracker. New Admissions of Patients with Confirmed COVID-
19, United States. https://covid.cdc.gov/covid-data-tracker/#new-hospital-admissions. (CDC, May 24, 2021b).
Centers for Disease Control and Prevention (CDC). (2021c, May 24).
Variant Proportions. https://covid.cdc.gov/covid-data-tracker/#variant-proportions. (CDC, May 24, 2021c).
Centers for Disease Control and Prevention (CDC). (2021d, May 24).
COVID-19 Weekly Deaths per 100,000 Population by Age by Age, Race/
Ethnicity, and Sex. https://covid.cdc.gov/covid-data-tracker/#demographicsovertime. (CDC, May 24, 2021d).
Dagan, N et al., (2021, February 24). BNT162b2 mRNA COVID-19 vaccine
in a nationwide mass vaccination setting. N Engl J Med. 384(15):
1412-1423. doi: 10.1056/NEJMoa2101765. Epub 2021 Feb 24. PMID:
33626250; PMCID: PMC7944975. (Dagan et al., February 24, 2021).
Deepak, et al., (2021, April 7). Glucocorticoids and B Cell
Depleting Agents Substantially Impair Immunogenicity of mRNA
Vaccines to SARS-CoV-2. medRxiv 2<IP_ADDRESS>54656. https://doi.org/10.1101/2<IP_ADDRESS>54656. (Deepak et al., April 7, 2021).

Food and Drug Administration (FDA). (2020, December 11). Emergency
use authorization for an unapproved product review memorandum
(Pfizer-BioNTech COVID-19 vaccine/BNT 162b2 mRNA-1273). https://www.fda.gov/emergency-preparedness-and-response/coronavirus-disease-2019-covid-19/pfizer-biontech-covid-19-vaccine. (FDA, December 11,
2020).
Food and Drug Administration (FDA). (2020, December 18). Emergency
use authorization for an unapproved product review memorandum
(Moderna COVID-19 vaccine/mRNA-1273). https://www.fda.gov/emergency-preparedness-and-response/coronavirus-disease-2019-covid-19/moderna-covid-19-vaccine. (FDA, December 18, 2020).
Food and Drug Administration (FDA). (2021, February 26). Janssen
COVID-19 vaccine. Vaccines and Related Biological Products Advisory
Committee, February 26, 2021 Meeting Briefing Document. https://www.fda.gov/media/146219/download. (FDA, February 26, 2021).
Gharpure, R et al., (2021, February 5). Early COVID-19 first-dose
vaccination coverage among residents and staff members of skilled
nursing facilities participating in the pharmacy partnership for
long-term care program--United States, December 2020-January 2021.
MMWR 2021; 70: 178-182. DOI: http://dx.doi.org/10.15585/mmwr.mm7005e2. (Gharpure et al., February 5, 2021).
Hall, VJ et al., (2021, April 23). COVID-19 vaccine coverage in
health-care workers in England and effectiveness of BNT162b2 mRNA
vaccine against infection (SIREN): A prospective, multicentre,
cohort study. Lancet. 2021 Apr 23: S0140-6736(21)00790-X. doi:
10.1016/S0140-6736(21)00790-X. Online ahead of print. PMID:
33901423. (Hall et al., April 23, 2021).
Howard, J. (2021, May 22). ``Response to request for an assessment
by the National Institute for Occupational Safety and Health,
Centers for Disease Control and Prevention, U.S. Department of
Health and Human Services, of the current hazards facing healthcare
workers from Coronavirus Disease-2019 (COVID-19).'' (Howard, May 22,
2021).
Keehner et al., (2021, May 6). SARS-CoV-2 infection after
vaccination in health care workers in California. New England
Journal of Medicine 384(18). (Keehner et al., May 6, 2021).
KFF. (2021, April 22). KFF COVID-19 Vaccine Monitor https://www.kff.org/coronavirus-covid-19/dashboard/kff-covid-19-vaccine-monitor-dashboard/. (KFF, April 22, 2021).
King, WC et al., (2021, April 24). COVID-19 vaccine hesitancy
January-March 2021 among 18-64 year old US adults by employment and
occupation. medRxiv; https://www.medrxiv.org/content/10.1101/2<IP_ADDRESS>55821v3. (King et al., April 24, 2021).
Levine-Tiefenbrun, M et al., (2021, February 8). Decreased SARS-CoV-
2 viral load following vaccination. medRxiv. 2021; https://www.medrxiv.org/content/10.1101/2<IP_ADDRESS>51283v1.full.pdf.
(Levine-Tiefenbrun, February 8, 2021).
Marks, M et al., (2021, February 2). Transmission of COVID-19 in 282
clusters in Catalonia, Spain: A cohort study. Lancet Infect Dis.
21(5): 629-636. doi: 10.1016/S1473-3099(20)30985-3. Epub 2021 Feb 2.
PMID: 33545090; PMCID: PMC7906723. (Marks et al., February 2, 2021).
Pawlowski, C et al., (2021, February 27). FDA-authorized COVID-19
vaccines are effective per real-world evidence synthesized across a
multi-state health system. medRxiv [Preprint posted online February
27, 2021]. https://www.medrxiv.org/content/10.1101/2<IP_ADDRESS>51623v3. (Pawlowski et al., February 27, 2021).
Roy, B et al., (2020, December 29). Health care workers' reluctance
to take the COVID-19 vaccine: A consumer-marketing approach to
identifying and overcoming hesitancy. https://catalyst.nejm.org/doi/full/10.1056/CAT.20.0676. (Roy et al., December 29, 2020).
Schrading, WA et al., (2021, February 19). Vaccination rates and
acceptance of SARS-CoV-2 vaccination among U.S. emergency department
health care personnel. Acad Emerg Med 28: 455-458. (Schrading et
al., February 19, 2021).
Shah, ASV et al., (2021, March 21). Effect of vaccination on
transmission of COVID-19: an observational study in healthcare
workers and their households. medRxiv. 2021 https://www.medrxiv.org/content/10.1101/2<IP_ADDRESS>53275v1. (Shah et al., March 21,
2021).
Swift, MD et al., (2021, April 26). Effectiveness of mRNA COVID-19
vaccines against SARS-CoV-2 infection in a cohort of healthcare
personnel. Clinical Infectious Diseases DOI: https://doi.org/10.1093/cid/ciab361. (Swift et al., April 26, 2021).
Tande, AJ et al., (2021, March 10). Impact of the COVID-19 Vaccine
on asymptomatic infection among patients undergoing pre-procedural
COVID-19 molecular screening. Clin Infect Dis. 2021 Mar 10: ciab229.
doi: 10.1093/cid/ciab229. Epub ahead of print. PMID: 33704435;
PMCID: PMC7989519. (Tande et al., March 10, 2021).
Teran, RA et al., (2021, April 30). Postvaccination SARS-CoV-2
infections among skilled nursing facility residents and staff
members--Chicago, Illinois, December 2020-March 2021. MMWR 70(17):
632-638. (Teran et al., April 30, 2021).
Thompson, MG et al., (2021, April 2). Interim estimates of vaccine
effectiveness of BNT162b2 and mRNA-1273 COVID-19 vaccines in
preventing SARS-CoV-2 infection among health care personnel, first
responders, and other essential and frontline workers--eight U.S.
locations, December 2020-March 2021. MMWR 70: 495-500. DOI: http://dx.doi.org/10.15585/mmwr.mm7013e3. (Thompson et al., April 2, 2021).
Xie, X et al., (2021, February 8). Neutralization of SARS-CoV-2
spike 69/70 deletion, E484K and N501Y variants by BNT162b2 vaccine
elicited sera. Nature Medicine. DOI: https://doi.org/10.1038/s41591-021-01270-4. (Xie et al., February 8, 2021).
III. Impact on Healthcare Employees
    Data on SARS-CoV-2 infections, illnesses, and deaths among
healthcare employees supports OSHA's finding that COVID-19 poses a
grave danger to these employees. Even fairly brief exposure (i.e., 15
minutes during a 24-hour period) can lead to infection, which in turn
can cause death or serious impairment of health. Employees in
healthcare settings include healthcare employees, who provide direct
patient care (e.g., nurses, doctors, and emergency medical technicians
(EMTs)), and healthcare support employees, who provide services that
support the healthcare industry and may have contact with patients
(e.g., janitorial/housekeeping, laundry, and food service employees).
Employees who perform autopsies are also considered to work in
healthcare. Most employees who work in healthcare perform duties that
put them at elevated risk of exposure to SARS-CoV-2.
    SARS-CoV-2 is introduced into healthcare settings by infected
patients, other members of the public, or employees. Workers in
healthcare settings that provide treatment to patients with suspected
or confirmed COVID-19 face a particularly elevated risk of contracting
SARS-CoV-2 (Howard, May 22, 2021). Once the virus is introduced into
the worksite, the virus can be transmitted from person-to-person at
close contact through inhalation of respiratory droplets. In limited
scenarios, it might also be transmitted through inhalation of aerosols,
which consists of small droplets and particles that can linger in the
air, especially in enclosed spaces with inadequate ventilation (CDC,
May 7, 2021). Less frequently, transmission is also possible when
someone touches a contaminated item or surface and then touches their
nose, mouth, or eyes (CDC, April 5, 2021).
    A 2021 cross-sectional study of 6,510 healthcare employees from the
Northwestern HCW SARS-CoV-2 Serology Cohort Study (conducted May 28-
June 30, 2020 in Illinois) shows that infections among healthcare
workers were not limited to doctors and nurses; healthcare
administrators had similar rates of seropositivity compared to
physicians, and support services had the highest seroprevalence (this
group included healthcare facility workers in

food service, environmental services, security, and patient access/
registration) (Wilkins et al., 2021). A meta-analysis published in the
American Journal of Epidemiologists compared data from 97 separate
studies and found evidence that COVID-19 infections were both common
(11% of the tested cohort of healthcare employees) and spread among
different healthcare worker occupations. In this study, however, nurses
had the highest rate of seroprevalence while most of the COVID-19-
positive medical personnel were working in hospital nonemergency wards
during screening (Gomez-Ochoa et al., January 2021).
    Healthcare employees who provide direct patient care are at high
risk of exposure to SARS-CoV-2 because they have close and sometimes
prolonged contact with patients who are infected or potentially
infected with SARS-CoV-2. This contact occurs when conducting physical
examinations and providing treatment and medical support. The risk can
be amplified when examining or treating a COVID-19 patient who has
symptoms such as coughing and difficulty breathing (leading to more
forceful inhalation and exhalation), both of which can result in the
release of more droplets that can be propelled further. Healthcare
employees who conduct, or provide support during, aerosol-generating
procedures on persons with suspected or confirmed COVID-19 also face a
greater risk of infection (Heinzerling et al., April 17, 2020).
Examples of procedures that can produce aerosols include intubation,
suctioning airways, use of high-speed tools during dental work, and use
of power saws during autopsies. A complete list of aerosol-generating
procedures, as defined by this ETS, is included in 29 CFR 1910.502(b).
Employees in healthcare are also at risk of exposure to SARS-CoV-2 if
they have close contact with co-workers while providing patient care or
performing other duties in enclosed areas such as a nursing station,
laundry room, or kitchen. Based on the biological mechanisms of SARS-
CoV-2 transmission, there is no doubt that some employees in healthcare
are at risk of exposure to SARS-CoV-2. Healthcare employees are
performing some job tasks that create an expectation of exposure to
people or human remains infected with COVID-19. The nature of caring
for a patient known to have COVID-19 or performing on autopsy on
someone who had COVID-19 increases the risk to employees performing
that task.
    This section summarizes recent studies about U.S. employees in
healthcare that illustrate the impact of COVID-19 in several types of
settings. Because the pandemic is recent and the evidence generated is
on the frontiers of science, studies are not available for every type
of employee in every type of healthcare setting. The peer-reviewed
scientific journal articles, government reports, and journal pre-print
articles described below establish the widespread prevalence of COVID-
19 among healthcare employees. OSHA's findings are based primarily on
the evidence from peer-reviewed scientific journal articles and
government reports. However, peer review for scientific journal
articles and the assembly of information for government reports and
other official sources of information take time, and therefore those
sources do not always reflect the most up-to-date information (Chan et
al, December 14, 2010). This is critical in the context of the COVID-19
pandemic, where new information is emerging daily. Therefore, OSHA has
supplemented peer-reviewed data and government reports with additional
information on occupational outbreaks contained in other sources of
media (e.g., newspapers). The reported information from newspapers can
provide further evidence of the impact of an emerging and changing
disease, especially for certain workers in healthcare and associated
occupations (e.g., laundry workers, janitors) that are not well
represented in the peer-reviewed scientific literature, and assist OSHA
in protecting these employees from the grave danger posed by
transmission of SARS-CoV-2. OSHA did not make findings based solely on
non-peer-reviewed sources such as pre-prints and news articles, but the
agency found that those sources sometimes provided useful information
when considered in context with more robust sources. Together, these
sources of information represent the best available evidence of the
impact on employees of the pandemic thus far.
    The peer-reviewed literature, government reports and, in a limited
number of cases, non-peer-reviewed articles illustrate a significant
number of infections among healthcare employees, but the types of
workplaces or conditions described are not the only ones in which a
grave danger exists. However, the studies add to the evidence that any
healthcare employee is at risk of exposure if they have close contact
with others who are suspected or confirmed to have COVID-19. The
studies also provide evidence that once SARS-CoV-2 is introduced into
the healthcare workplace (e.g., through an infected patient, other
member of the public, or employee), unvaccinated employees in that
workplace are at risk of exposure.
a. General Investigations of Workers or Workplaces
    The Washington State Department of Health and the Washington State
Department of Labor and Industries collaborated on a report evaluating
COVID-19 cases and their occupational history (WSDH and WLNI, November
10, 2020). They identified 30,895 confirmed cases of COVID-19 in
Washington State with occupational data, including healthcare settings,
through September 13, 2020. They reported infection rates for 22
occupational groups, and reported that healthcare and social assistance
were among the industry sectors with the highest incidence of
infections (WSDH and WLNI, November 10, 2020). The report states that
some occupations increase the risk to workers of exposure to SARS-CoV-
2, but the data does not demonstrate that all the cases reported
resulted from occupational exposure.
    These data were also used to determine how work activities were
related to COVID-19. Zhang used information from a previous Washington
State report with an earlier cutoff date (through June 11, 2020; 10,850
cases) and cross-referenced it with information available from O*NET (a
Department of Labor database that contains detailed occupational
information for more than 900 occupations across the U.S.) to determine
occupation-specific COVID-19 risks (Zhang, November 18, 2020). Zhang
created a model using the O*NET descriptors and correlated it to the
case reports from Washington State to develop a predictive model for
COVID-19 cases. The model found that among O*NET's 57 physical and
social factors related to work, the two predictive variables of COVID-
19 risk were frequency of exposure to diseases and physical proximity
to other people. The author found that healthcare professions in
general had the highest predicted risk for COVID-19. This finding
provides additional evidence that during an active pandemic, healthcare
employees can be exposed to a grave danger during sustained periods in
workspaces where they are working in proximity to others, including
patients with COVID-19.
    The Oregon Health Authority (OHA) publishes a weekly report
detailing outbreaks directly related to work settings. OHA
epidemiologists consider cases to be part of a workplace outbreak when
clusters form with respect to space and time unless their

investigation uncovers an alternative source for the outbreak. In their
May 19, 2021, COVID-19 Weekly Report, OHA reported 71 active clusters,
including at three separate hospitals (OHA, May 19, 2021).
    In a May 21, 2021 report, the Tennessee Department of Health
reported 238 active clusters (i.e., 2 or more confirmed cases of COVID-
19 linked by the same location of exposure or exposure event that is
not considered a household exposure), with 6 occurring in assisted care
facilities, 37 in nursing homes, and 3 in other healthcare settings
(Tennessee Department of Health, May 21, 2021).
    A study on SARS-CoV-2 testing in Los Angeles from mid-September
through October 2020 evaluated 149,957 symptomatic and asymptomatic
positive cases associated with an occupation (Allan-Blitz et al.,
December 11, 2020). Infection rates were found to be particularly high
for healthcare personnel and first responders.
    A Morbidity and Mortality Weekly Report (MMWRs) (a weekly
epidemiological digest published by the CDC) reported on the
occupational status of COVID-19 cases in Colorado. In the Colorado
study, 1,738 COVID-19 cases from nine Colorado counties were evaluated;
these cases occurred before the state lockdown that began on March 26,
2020 (Marshall et al., June 30, 2020). Half of the individuals were
exposed in a workplace setting, with the greatest number of COVID-19-
positive employees coming from healthcare (38%).
    Chen et al., (January 22, 2021) analyzed records of deaths
occurring on or after January 1, 2016 in California and found that
mortality rates in working aged adults (18-65 years) increased 22%
during the COVID-19 pandemic (March through October 2020) compared to
pre-pandemic periods. Relative to pre-pandemic periods, healthcare or
emergency workers were one occupational group that experienced excess
and statistically significant mortality compared to pre-pandemic
periods (19% increase). The study authors concluded that essential work
conducted in person is a likely avenue of infection transmission.
    Hawkins et al., (January 10, 2021) examined death certificates of
individuals who died in Massachusetts between March 1 and July 31,
2020. An age-adjusted mortality rate of 16.4 per 100,000 employees was
determined from 555 death certificates that had useable occupation
information. Employees in healthcare support, personal care services,
and social services had particularly high mortality rates. The study
authors noted that occupation groups expected to have frequent contact
with sick people, close contact with the public, and jobs that are not
practical to do from home had particularly elevated mortality rates.
    The impact of COVID-19 across diverse healthcare sectors is not
limited to the United States. The European Centre for Disease
Prevention and Control investigated clusters in occupational settings
throughout Europe (ECDC, August 11, 2020). The Centre reviewed 1,376
occupational clusters from 16 European countries from March through
July of 2020. Indoor settings contributed to 95% of reported clusters.
Hospitals and long-term care facilities accounted for many of the
clusters.
References
Allan-Blitz, L et al., (2020, December 11). High frequency and
prevalence of community-based asymptomatic SARS-CoV-2 Infection.
medRxix. https://doi.org/10.1101/2<IP_ADDRESS>46249. (Allan-Blitz
et al., December 11, 2020).
Centers for Disease Control and Prevention (CDC). (2021, April 5).
Science Brief: SARS-CoV-2 and Surface (Fomite) Transmission for
Indoor Community Environments. https://www.cdc.gov/coronavirus/2019-ncov/more/science-and-research/surface-transmission.html. (CDC,
April 5, 2021).
Centers for Disease Control and Prevention (CDC). (2021, May 7).
Scientific Brief: SARS-CoV-2 Transmission. https://www.cdc.gov/coronavirus/2019-ncov/more/scientific-brief-sars-cov-2.html. (CDC,
May 7, 2021).
Chan, E et al., (2010, December 14). Global capacity for emerging
infectious disease detection. Proceedings of the National Academy of
Sciences of the United States of America, 107(50), 21701-21706.
https://doi.org/10.1073/pnas.1006219107. (Chan et al, December 14,
2010).
Chen, Y et al., (2021, January 22). Excess mortality associated with
the COVID-19 pandemic among Californians 18-65 years of age, by
occupational sector and occupation: March through October 2020.
MedRxiv. doi: 10.1101/2<IP_ADDRESS>50266. (Chen et al., January 22,
2021).
European Centre for Disease Prevention and Control (ECDC). (2020,
August 11). COVID-19 clusters and outbreaks in occupational settings
in the EU/EEA and the UK. (ECDC, August 11, 2020).
G[oacute]mez-Ochoa, SA et al., (2021, January). COVID-19 in health-
care workers: a living systematic review and meta-analysis of
prevalence, risk factors, clinical characteristics, and outcomes.
American journal of epidemiology. 2021 Jan; 190(1): 161-75. (Gomez-
Ochoa et al., January 2021).
Hawkins, D et al., (2020, December 21). COVID-19 deaths by
occupation, Massachusetts, March 1-July 31, 2020. American Journal
of Industrial Medicine 64(4): 238-244. DOI: 10.1002/ajim.23227.
(Hawkins et al., December 21, 2021).
Heinzerling, A et al., (2020, April 17). Transmission of COVID-19 to
Health Care Personnel During Exposures to a Hospitalized Patient--
Solano County, California, February 2020. MMWR Morb Mortal Wkly Rep
2020; 69: 472-476. DOI: http://dx.doi.org/10.15585/mmwr.mm6915e5.
(Heinzerling et al., April 17, 2020).
Howard, J. (2021, May 22). ``Response to request for an assessment
by the National Institute for Occupational Safety and Health,
Centers for Disease Control and Prevention, U.S. Department of
Health and Human Services, of the current hazards facing healthcare
workers from Coronavirus Disease-2019 (COVID-19).'' (Howard, May 22,
2021).
Marshall, K et al., (2020, June 30). Exposure before issuance of
stay-at-home orders among persons with laboratory-confirmed COVID-
19--Colorado, March 2020. MMWR: 69(26): 847-9. (Marshall et al.,
June 30, 2020).
Oregon Health Authority (OHA). (2021, May 19). COVID-19 weekly
outbreak report. https://www.oregon.gov/oha/covid19/Documents/DataReports/COVID-19-Weekly-Outbreak-Report-2021-1-13-FINAL.pdf.
(OHA, May 19, 2021).
Tennessee Department of Health. (2021, May 21). COVID-19 critical
indicators. (Tennessee Department of Health. May 21, 2021).
Washington State Department of Health (WSDH) and Washington State
Department of Labor and Industries (WLNI). (2020, November 10).
COVID-19 confirmed cases by industry sector. Publication Number 421-
002. https://www.doh.wa.gov/Portals/1/Documents/1600/coronavirus/IndustrySectorReport.pdf. (WSDH and WLNI, November 10, 2020).
Wilkins, JT et al., (2021). Seroprevalence and correlates of SARS-
CoV-2 antibodies in health care workers in Chicago. Open Forum
Infectious Diseases. 8(1): ofaa582. https://doi.org/10.1093/ofid/ofaa582. (Wilkins et al., 2021).
Zhang, M. (2020, November 18). Estimation of differential
occupational risk of COVID-19 by comparing risk factors with case
data by occupational group. American Journal of Industrial Medicine
64(1):39-47. doi: 10.1002/ajim.23199. (Zhang, November 18, 2020).
b. Studies Focusing on Employees in Healthcare
General Surveillance and Surveys Across the U.S.
    Burrer et al., (2020) reported surveillance data on COVID-19 cases
and deaths among ``healthcare personnel'' between February 12 and April
9, 2020. ``Healthcare personnel'' were defined as ``paid and unpaid
persons serving in healthcare settings who have the potential for
direct or indirect exposure to patients or

infectious materials.'' \9\ Although only 16% of all surveillance forms
indicated whether the case was healthcare personnel, 19% of the
reported cases occurred in healthcare personnel. Twelve states
indicated whether the case was healthcare personnel for at least 80% of
all reported cases. An estimated 11% of COVID-19 cases from those 12
states were healthcare personnel. Based on reported known contact with
confirmed COVID-19 cases in the 14 days before illness onset, work
exposures likely caused 55% of those infections. Between 8% and 10% of
infected employees were hospitalized, 2%-5% of the infected employees
were admitted to the ICU, and 0.3%-0.6% of those employees died.
---------------------------------------------------------------------------

    \9\ The term ``healthcare personnel'' is consistent with OSHA's
use of the terms ``healthcare employees'' and ``healthcare workers''
to include healthcare support workers.
---------------------------------------------------------------------------

    CDC continues to provide general updates for COVID-19 cases and
deaths among healthcare personnel. However, information on healthcare
personnel status was reported for only 18.21% of total cases and death
status reported for only 79.57% of healthcare personnel cases as of May
24, 2021 (CDC, May 24, 2021a). CDC reports 491,816 healthcare personnel
cases (10% of the 4,856,885 cases that included information on
healthcare personnel status) and 1,611 fatalities (0.4% of healthcare
employee cases) as of May 24, 2021 (CDC, May 24, 2021a). Independent
reporting by Kaiser Health News and the Guardian in their ongoing
investigative reporting database found 3,607 fatalities among
healthcare personnel in the United States as of April 2021(Kaiser
Health News and the Guardian, April 2021; February 23, 2021). The
reporters for this effort consider even their own count--which is
higher than the official CDC count--to be an undercount due to various
reporting issues, such as a lack of reporting requirements for long-
term care employees for a significant portion of the initial COVID-19
surge.
    Hartmann et al., (2020) analyzed case interview data from February
through May 2020 to assess the burden of COVID-19 on healthcare
employees in Los Angeles County, CA, where it is mandated that all
positive cases be reported to the County Department of Public Health,
and all cases are interviewed. Healthcare employees were defined as any
person working or volunteering in healthcare settings including
hospitals and skilled nursing facilities, medical offices, mental
health facilities, and emergency medical services (EMS). The definition
also includes healthcare employees providing care in non-healthcare
settings such as schools, senior living facilities, and correctional
facilities. Healthcare employees included both staff who interacted
directly with patients and staff who do not provide direct clinical
care to patients. Through May 31, 2020, 5,458 COVID-19 cases among
healthcare employees were reported to the County Health Department,
representing 9.6% of all cases during this time period. Of those
healthcare employees, 46.6% worked in a long-term care setting, 27.7%
worked in a hospital, and 6.9% worked in medical offices. Healthcare
employees from all other settings represented less than 4% of total
healthcare employee cases. Nurses represented 49.4% of all healthcare
employee cases; no other group of healthcare employees represented more
than 6% of the total reported healthcare employee cases. Of note is
that some healthcare associated employees who are expected to have less
close contact with patients represented a greater percentage of cases
than some healthcare employee that are expected to have close and
direct patient contact. For example, employees in administration
(4.3%), environmental services (3.2%), and food services (2.9%)
represented a higher percentage of infected healthcare employees than
physicians (2.7%). When asked about known exposures, 44% of those who
tested positive reported exposure to a COVID-19-positive patient or co-
worker in their health facility, 11% reported exposure to a COVID-19-
positive friend or family member or recent travel, and 45.1% had
unknown exposures. At the time of the interviews, 5.3% of COVID-19-
positive healthcare employees in Los Angeles County reported requiring
hospitalization because of COVID-19, and as of May 31, 2020 there were
40 (0.7%) deaths.
    Fell et al., (October 30, 2020) reviewed exposure and infection
data for healthcare personnel in Minnesota between March and July of
2020. After the first confirmed case of COVID-19 in Minnesota (on March
6, 2020), the Minnesota Department of Health (MDH) requested that
healthcare facilities provide a list of exposed healthcare personnel.
Healthcare personnel included EMS personnel, nurses/nursing assistants,
physicians, technicians, therapists, phlebotomists, pharmacists,
students and trainees, contractors, and those who do not provide direct
patient care but could be exposed to infectious agents in a healthcare
setting (e.g., clerical, food services, environmental services,
laundry, security, engineering and facilities management,
administrative, billing, and volunteer personnel). Cases in laboratory
personnel are also reported. The facilities were asked to determine if
each exposure was high-risk, defined as when the healthcare personnel
has close, prolonged contact with a confirmed COVID-19 case or their
secretions/excretions while not wearing PPE, or close, prolonged
contact with persons with COVID-19 in their household or community. MDH
and the 1,217 participating healthcare facilities assessed 17,200
healthcare personnel for 21,406 exposures to COVID-19 cases, of which
5,374 (25%) were classified as higher-risk. It was reported that 373 of
5,374 personnel (6.9%) with high-risk exposures tested positive for
COVID-19 within 14 days of the exposure. The report stated that only
symptomatic personnel were encouraged to get tested for COVID-19, and
therefore it is possible that asymptomatic cases occurred and were not
detected. Of those 373 personnel who tested positive for COVID-19, 242
were exposed to a patient, resident of a congregate setting, in a
congregate setting outbreak, or to another healthcare personnel.
Twenty-one percent of exposures to a confirmed COVID-19 case took place
in acute or ambulatory care settings, 24% of exposures were to
residents in congregate living or long-term care settings, and 25% of
exposures were in congregate setting outbreaks. An additional 25% of
exposures to confirmed COVID-19 cases were exposures to co-workers, and
5% were exposures to household/social contacts.
    The Fell study (October 30, 2020) also demonstrated that high risk
exposures can occur to healthcare employees in positions throughout the
healthcare facility. Available data for 4,669 (87%) of the higher risk
exposures in the Fell et al., study indicated that the highest
percentages of high-risk exposures were in nursing assistants or
patient care aides (1,857; 40%) and nursing staff (1,416; 30%). The
proportion of high-risk exposures represented by personnel such as
administrators (247; 5%) and environmental services staff (155; 3%)
were similar to those reported by medical providers, such as physicians
or nurse practitioners (220; 5%). Healthcare personnel working in
congregate living or long-term care settings, including skilled
nursing, assisted living, and group home facilities, were more likely
to receive a positive COVID-19 test result within 14 days of a higher-
risk exposure than were healthcare personnel working in acute care
settings. The study authors note the

potential for employee transmission by cautioning that, in contrast to
the recognized risk associated with patient care, healthcare employees
might have failed to recognize the risk associated with interacting
with co-workers in areas such as breakrooms and nursing stations.
Physical distancing and PPE may therefore not have been used as
consistently in those situations.
    The authors of a different study concluded that nurses and EMTs
were, respectively, 26% and 33% more likely to contract COVID-19 than
attending physicians. Nurses and EMTs' job duties require more intense,
close contact with patients compared to physicians, as well as higher
frequency and duration of patient contact. Firew et al., (October 21,
2020) conducted a cross-sectional survey of healthcare employees in May
of 2020 across 48 states, the District of Columbia, and U.S.
territories. The 2,040 respondents who completed at least 80% of the
survey were included in the study. Among included participants, 31.1%
were attending physicians, 26.8% were nurses, 13% were EMTs, 8.82% were
resident physicians or fellows, 3.97% were physician assistants, and
16.32% were other healthcare employees. A total of 598 respondents
(29.3%) reported SARS-CoV-2 infections.
    In a prospective study of over 2 million community members and
99,795 frontline healthcare workers that was performed in the U.S. and
UK from March through April 2020, healthcare workers were 3.4 times as
likely to self-report a positive COVID-19 test as the general public,
after adjusting for the increased likelihood of healthcare personnel
receiving a COVID-19 test (Nguyen et al., 2020). In the U.S. alone,
healthcare workers were almost two times more likely to report a
positive test after adjusting for greater likelihood of testing.
Detection of SARS-CoV-2 in Healthcare Employees
    OSHA reviewed a number of studies that included hospital employees.
Many hospitals provide short-term and/or long-term care for COVID-19
patients who have symptoms that are severe enough to require
hospitalization. Therefore, close contact with COVID-19 patients is
expected in hospital settings, putting hospital employees at risk of
developing COVID-19. Examples of employees who work in hospitals
include healthcare practitioners, who generally have either licensure
or credentialing requirements (e.g., doctors, nurses, pharmacists,
physical therapists, massage therapists) for the purpose of promoting,
maintaining, monitoring, or restoring health. Individuals who provide
healthcare support services also work at hospitals. Examples of
employees who provide healthcare support services and may have close
contact with COVID-19 patients in some circumstances include patient
intake/admission, patient food services, chaplain services, equipment
and facility maintenance, housekeeping services, healthcare laundry
services, and medical waste handling services. As noted above, hospital
employees are at risk from close contact with patients.
    Some of the studies reviewed below were done in employees of
healthcare systems that included both hospitals and ambulatory care
centers such as physician offices, medical clinics (including urgent
care and retail-based clinics), outpatient surgical centers, and
outpatient cancer treatment centers. Although this ETS does not cover
non-hospital ambulatory care settings where all non-employees are
screened prior to entry and people with suspected or confirmed COVID-19
are not permitted to enter, it was not possible to separate out results
for hospital versus ambulatory care employees. Also it is not known to
what extent those ambulatory care centers in the studies reviewed by
OSHA performed screening to identify suspected or confirmed COVID-19.
Risk of exposure and transmission of SARS-CoV-2 is expected to be lower
in ambulatory healthcare settings that perform screening to exclude
persons with suspected or confirmed COVID-19. However some types of
ambulatory medical facilities (e.g., family practice; pediatrics
clinic; urgent care) may choose to test patients for COVID-19 or
examine and treat COVID-19 patients on site. Therefore, healthcare
employees and healthcare support employees in some ambulatory care
centers who do not conduct health screening to identify and exclude
suspected or confirmed COVID-19 patients are at risk of infection due
to close contact with patients who could potentially have COVID-19.
    Barrett et al., (2020) conducted a prospective cohort study of
healthcare employees and non-healthcare employees with no known
previous SARS-CoV-2 infection who were recruited and tested for SARS-
CoV-2 from March 24 through April 7, 2020 at Rutgers University and two
of its affiliated university hospitals in New Jersey. As of July 2020,
New Jersey was one of the hardest hit areas, with less than 3% of the
U.S. population but 8.5% of all known U.S. cases. Healthcare employees
were defined as individuals who worked at least 20 hours per week in a
hospital, had occupations with regular patient contact, and were
expected to have contact with at least three patients per shift over
the following three months. Occupations included residents, fellows,
attending physicians, dentists, nurse practitioners, physician
assistants, registered nurses, technicians, respiratory therapists, and
physical therapists. Non-healthcare employees included faculty, staff,
trainees, or students working at Rutgers for at least 20 hours a week
and who had no patient contact. The study reported that 7.3% of
healthcare employees (40 of 546) and 0.4% of non-healthcare employees
(1 of 283) tested positive for SARS-CoV-2 infection. Even after the
authors conducted sensitivity analyses to exclude individuals with
symptoms at baseline and those who had exposure to someone with COVID-
19 or COVID-19 symptoms outside of work, differences between infection
rates in healthcare employees and non-healthcare employees continued to
be observed. OSHA finds this suggests that healthcare employees were
more likely than non-healthcare employees to have developed COVID-19
from a workplace exposure during the early months of the pandemic in
the United States. The study authors concluded that the potential for
workplace exposure is further supported by the fact that only 8% of
infected study subjects reported contact with someone having COVID-19
symptoms outside of work. In addition, higher rates of infection were
observed in healthcare employees who worked in the hospital that had
more COVID-19 patients and was located in the community that had higher
rates of SARS-CoV-2 infections. The study authors noted that because
that hospital was overwhelmed, it was not always possible to separate
COVID-19 vs. non-COVID-19 patients, which may have led to additional
exposures among staff. Among healthcare employees, nurses had the
highest rate of observed infections (11.1% tested positive), and
attending physicians had the lowest rate of observed infection (1.8%
positive). Resident and fellow physicians had a 3.1% positivity rate
and other groups of healthcare employees had a 9% positivity rate.
Increased risk of infection was associated with spending greater
proportions of work time in patients' rooms and higher reported
exposures to patients with suspected or diagnosed COVID-19.
    Mani et al., (November 15, 2020) reported results from SARS-CoV-2
testing of 3,477 symptomatic employees in the University of Washington

Medical system and its affiliated organizations in Seattle, WA, between
March 12 and April 23, 2020. During that period, 185 (5.3%) employees
tested positive. Prevalence (i.e., proportion) of SARS-CoV-2 in
frontline healthcare employees (those with face-to-face contact with
patients) was 5.2% and prevalence in non-frontline staff was 5.5%. Some
staff who were asymptomatic also underwent screening as part of
outbreak investigations, and 9 of 151 (6%) tested positive. When
findings from symptomatic and asymptomatic staff were combined, SARS-
CoV-2 prevalence was 5.3% in frontline healthcare employees and 5.3%
among all employees. Of the 174 employees who tested positive and were
followed, six (3.2%) reported COVID-related hospitalization, and one
employee was admitted to the ICU. No deaths were reported. The study
authors suspected that community transmission likely played a major
role in infection among healthcare employees early in the local
epidemic and that similar percentages of infections in frontline and
non-frontline healthcare employees support the PPE protocols
implemented for frontline workers at the institution. In addition,
positive cases were likely underestimated due to the focus on testing
symptomatic employees.
    Vahidy et al., (2020) studied asymptomatic infection rates among
staff from a medical center consisting of seven hospitals in Texas and
members of the surrounding community in March through April of 2020.
Healthcare jobs with possible exposure to COVID-19 patients were
classified into five categories, with varying levels of patient
exposure: (1) Nursing (e.g., nurses/nurses aids, emergency medical
technicians), (2) clinicians (e.g., physicians, nurse practitioners),
(3) allied healthcare workers (e.g., therapists, social workers), (4)
support staff (e.g., security, housekeeping), and (5) administrative or
research staff (e.g., managers, research assistants). A total of 2,872
asymptomatic individuals, including 2,787 healthcare personnel and 85
community residents, were tested for SARS-CoV-2 infection. Among the
healthcare personnel tested, the prevalence of SARS-CoV-2 infection was
5.4% among the 1,992 patient-facing staff treating COVID-19 patients
and 0.6% among the 625 patient-facing staff not treating COVID-19
patients. No cases were seen among the 170 nonclinical healthcare staff
that did not interact with patients or in the 85 community residents
(Vahidy et al., 2020). The nonclinical healthcare staff worked in
buildings with separate heating, ventilation, and air conditioning
systems, and with lower population density because of remote work when
compared to clinical healthcare staff. In the different healthcare
categories that cared for COVID-19 patients, prevalence of infection
ranged from 3.6% to 6.5%, with no significant differences in the
different categories of healthcare workers. Therefore, the study
indicates that healthcare workers providing both direct and indirect
care to COVID-19 patients are at risk.
    Nagler et al., (June 28, 2020), reported the results of SARS-CoV-2
testing in employees from the New York Langone Health system, an
academic medical center encompassing four hospital campuses and over
250 ambulatory sites, with approximately 43,000 employees. Between
March 25 and May 18, 2020, the health system tested employees who were
symptomatic (4,150), were asymptomatic but exposed to COVID-19 (4,362),
and asymptomatic employees who were returning to work after their
services had been suspended during the peak of the epidemic (6,234).
Among symptomatic employees, the COVID-19 positivity rate across the
duration of the study was 33%. Among asymptomatic employees with self-
reported exposure, the COVID-19 positivity rate was 8%. In asymptomatic
employees returning to work, COVID-19 positivity rate was 3%. In all
groups, the positivity rate in the first week of testing was
substantially higher than in the last week of testing, which occurred
more than a month after the first week. The study authors noted a
temporal correlation of COVID-19 case declines in healthcare employees
and the community, despite continued workplace exposure, and suggested
that infections in healthcare employees may reflect importance of
community transmission and efficacy of stringent infection control and
PPE standards that remained largely unchanged since the start of the
pandemic in March 2020. OSHA finds that the study demonstrates the
potential for COVID-19 to be introduced into the workplace from
uncontrolled community spread and that the effective use of infection
control practices and PPE most likely prevented transmission to
healthcare employees.
    Misra-Hebert et al., (September 1, 2020) conducted a retrospective
cohort study to obtain data on rates of COVID-19 and risk factors for
severe disease in healthcare employees and non-healthcare employees
(neither category defined) who were tested for SARS-CoV-2, and listed
in a registry at the Cleveland Clinic Health System, between March 8
and June 9, 2020. The data was drawn from healthcare employees from
different segments of the country. Ninety percent of the healthcare
employees and 75% of non-healthcare employees were from Ohio, and the
remainder were from Florida. Although more healthcare employees than
non-healthcare employees reported exposures to COVID-19 (72% vs. 17%),
similar, and not significantly different, proportions of employees
tested positive for COVID-19 in each group: 9% (551/6145) of healthcare
employees and 6.5% (4353/66,764) of non-healthcare employees. OSHA
finds it difficult to draw conclusions regarding this finding because
the nature of the exposure (e.g., whether it was at close contact) was
not explained. In fact, patient-facing healthcare employees (those
having direct contact with patients) were 1.6 times more likely than
non-patient-facing healthcare employees to test positive. The study
authors suggested that the finding represents an increased risk of
infection with work exposure, however they were not able to confirm if
the exposure occurred 14 days prior to testing or if PPE was worn
during the exposure. Positive cases peaked in early-to-mid April for
both healthcare employees and non-healthcare employees (16% and 12%,
respectively, as estimated from figure 2 of the study), and then
decreased concurrently with the implementation of preventive measures,
such as masking and physical distancing, over the course of the study.
Of those who tested positive, 6.9% of healthcare employees and 27.7% of
non-healthcare employees were hospitalized, and 1.8% and 10.8%
respectively, were admitted to the intensive care unit. The study noted
that the lower rates of hospitalization for the healthcare employee
group could be explained on the basis that the healthcare employee
population was younger and had fewer co-morbidities.
Serology Testing in Employees in Hospitals.
    Although most of the studies described in this section relied on
polymerase chain reaction (PCR) tests to detect cases of COVID-19, a
number of studies conducted serology testing to determine how many
individuals had been infected by the SARS-CoV-2 virus in the past.
Serology tests determine if antibodies that respond to the SARS-CoV-2
virus are present in samples of blood serum. Seroprevalence is the
percentage of individuals in a population who have antibodies. Terms
such as seropositive or seroconversion are often used to describe
persons who have tested positive for the SARS-CoV-2 antibody. Most of
the serology tests

conducted looked at a type of antibody known as Immunoglobulin G (IgG).
Seroprevalence studies provide a more complete picture of how many
individuals in a population may have been infected because many
individuals who were infected were not tested for current infections
for reasons such as lack of symptoms and lack of available testing.
Indeed, many individuals who were asymptomatic may be unaware that they
were exposed to SARS-CoV-2 or had COVID-19 (CDC, July 6, 2020). The
studies described below were conducted before vaccination began, and it
is therefore unlikely that the studies are detecting antibodies
produced as a result of vaccination.
    Venugopal et al., (2020) conducted a cross-sectional study of
healthcare employees across all hospital services (including
physicians, nurses, ancillary services, and ``others'') who worked at a
level one trauma center in the South Bronx, NY between March 1 and May
1, 2020. The period of analysis included the first few weeks of March,
when New York City experienced a surge of infections that resulted in
strained resources and supplies such as PPE. This hospital was so
highly impacted that it was considered ``the epicenter of the
epicenter.'' Participants were tested for IgG antibodies. They were
also tested for SARS-CoV-2. Of the 500 out of 659 healthcare employees
who completed serology testing, 137 (27%) were positive for SARS-CoV-2
IgG antibodies. Seroprevalence was similar across the different types
of healthcare employees (25% to 28%). The study authors indicated that
seroprevalence in healthcare employees was higher than in the
community, and that seroprevalence likely reflected healthcare and
community exposures.
    Sims et al., (November 5, 2020) conducted a prospective cohort
serology study at Beaumont Health, which includes eight hospitals
across the Detroit, MI metropolitan area. In April of 2020, during the
peak of the pandemic's first wave, Michigan had the third highest
number of cases in the U.S. and most cases were in the Detroit
metropolitan area. All 43,000 hospital employees were invited to
participate and seroprevalence was analyzed in 20,614 of them between
April 13 and May 28, 2020. A total of 1,818 (8.8%) of participants were
seropositive. However, when separated according to employees working at
home (n=1,868) versus working in their normal manner, employees working
at home were significantly less likely to be seropositive (5.6%) than
those going into work (9.1%). The authors speculated that the
seropositivity level for employees working at home was representative
of the population sheltering at home and only leaving home when
necessary. Participants involved with direct patient care had a higher
seropositive rate (9.5%) than those who were not (7%). Healthcare
employees with frequent patient contact (phlebotomy, respiratory
therapy, and nursing) had a significantly higher seropositive rate
(11%) than those with intermittent patient contact (physicians or
clinical roles such as physical therapists, radiology technicians,
etc.), who on average had a seropositive rate of 7.4%. The study
authors speculated that the differences in these two groups may have
been based on differences in both duration and proximity of exposure to
patients. Another notable observation is that support personnel such as
facilities/security and administrative support employees had
seropositivity rates of approximately 7% to 8%, which were similar to
rates in physicians (values estimated from Figure 2B). Participants
reporting frequent contact with either 1) non-COVID-19 patients, or 2)
physicians or nurses but not patients, had higher rates of
seropositivity (7.6%) than those reporting no significant contact with
patients, physicians, or nurses (but who handled patient samples)
(6.5%).
    Moscola et al., (September 1, 2020) reported the prevalence of
SARS-CoV-2 antibodies in healthcare employees from the Northwell Health
System in the greater New York City area. The healthcare employees were
offered free, voluntary testing at each of the system's 52 sites
between April 20 and June 23, 2020. The analysis included 40,329 of the
system's 70,812 employees and found that 5,523 (13.7%) were
seropositive. The prevalence of SARS-CoV-2 antibodies was similar to
that found in randomly-tested adults in New York State at that time
(14%). Analysis of seropositivity by job type reported the highest
levels of seropositivity (20.9%) in service maintenance staff
(including housekeepers, groundskeepers, medical assistants, and 21
others), followed by 13.1% in nurses, 12.6% in administrative and
clerical staff (including non-clinical professionals such as employees
in information technology, human resources, medical records, and
billing); 11.6% in allied health professionals (including clinical
professionals such as physician assistants, physical therapists/
occupational therapists, social workers, mental health professionals,
pharmacists, and laboratory technicians), and 8.7% in physicians.
Seropositivity rates were highest in employees from the emergency
department and non-ICU hospital units (approximately 17% each),
followed by ``other'' non-specified areas (12.1%), and ICUs (9.9%).
    Wilkins et al., (2021) conducted a cross-sectional study to examine
seropositivity rates in 6,510 healthcare workers from a Chicago
healthcare system consisting of hospitals, immediate care centers, and
outpatient practices. Blood samples were collected through July 8,
2020. The study authors then compared the seropositivity rate of
different occupational groups of workers, using administrators as the
referent group to reflect exposure consistent with non-healthcare
workers. Overall seropositivity for all study participants was 4.8%.
Before adjusting for demographics and self-reported out-of-hospital
exposure to COVID-19, the study found that a number of healthcare
occupations had a higher crude prevalence rate than the administrator
group, including: 10.4% for support service healthcare workers; 10.1%
for medical assistants; 9.3% for respiratory technicians; 7.6% for
nurses; and 3.8% for administrators. After adjustment for demographics
and self-reported out-of-hospital exposure to COVID-19, the only type
of healthcare workers that continued to be significantly more likely to
be seropositive than administrators were nurses, who were 1.9 times
more likely to be seropositive. The study authors concluded that the
higher work-related risk in nurses likely occurred as a result of
frequent and close contact with patients. The study also compared
seropositivity rates for different occupational tasks and found that
adjusted seropositivity rates were higher for workers participating in
the care of COVID-19 patients when compared with those who did not
report participating in the care of COVID-19 patients. Being exposed to
patients receiving high-flow oxygen therapy and hemodialysis was
significantly associated with 45% and 57% higher odds for seropositive
status, respectively.
Comparison of Healthcare Worker Serology and the Surrounding Community
    Although some serology studies suggest that infections are more
correlated to community transmission than job designation (Jacob et
al., March 10, 2021; Carter et al., May 2021), these studies do not
undermine the robust evidence that healthcare employees with potential
workplace exposure to patients with suspected or confirmed COVID-19 are
exposed to an elevated risk of contracting COVID-19 compared

to the general population. Carter et al., (May 2021) found that
healthcare worker infection rates varied from region to region, noting
the importance of community transmission as a factor in infection
rates. In Jacob et al., (March 10, 2021), health care workers' serology
results were compared to residence location, job designation, and other
characteristics to identify risk factors. The study authors found that
community transmission was a significant factor in acquiring
infections, but were not able to tie in any specific job designation
resulting in increases in infection risk. The authors note, however,
that the study did not show that workplace exposures did not increase
risk; rather it showed that the levels of community transmission
observed may be a greater driver of transmission. It should also be
noted that the non-pharmaceutical interventions for each job
classification are different, so a direct comparison of non-clinical
and clinical personnel may result in conclusions with limited
application.
    One might expect that a full shift with fully and properly
implemented non-pharmaceutical interventions should result in lower
infection rates. This appeared evident in a study comparing infection
rates between first and second COVID-19 outbreak surges in Norway
(Magnusson et al., January 6, 2021). For instance, during the first
wave from February 26, 2020 to July 17, 2020, nurses were almost three
times more likely to be infected than those in a similar age range (20
to 70 years old). However, during the second wave from July 18, 2020 to
December 18, 2020, infection rates for nurses were largely
indistinguishable from the population at large of a similar age. The
authors suggested that the decrease in the odds ratio was potentially
due to the implementation of appropriate infection control practices
that were previously lacking.
Studies Examining Risks After Known Exposures
    Heinzerling et al., (April 17, 2020) examined the development of
COVID-19 in 120 healthcare employees who were unknowingly exposed to a
patient with COVID-19. The patient was later identified as one of the
first U.S. community cases of COVID-19, and Heinzerling et al., (April
17, 2020) concluded that the ``investigation presented a unique
opportunity to analyze exposures associated with SARS-CoV-2
transmission in a healthcare setting without recognized community
exposures.'' Of the 120 healthcare employees who were exposed, 43
developed symptoms within 14 days of exposure and were tested for
COVID-19. Three of those employees (7% of those tested) were positive
for COVID-19. Although those three employees represent 2.5% of the
total exposed, it is possible that more employees might have developed
COVID-19 because asymptomatic employees were not tested. The healthcare
employees who became infected, when compared to those who were not
infected, were more commonly present during two aerosol-generating
procedures (nebulizer treatment (67% vs. 9%) and non-invasive
ventilation (67% vs. 12%); more commonly performed physical
examinations of the patient (100% vs. 24%); and were exposed to the
patient for longer durations of time (median 120 minutes vs. 25
minutes). None of the exposed healthcare employees had been wearing the
complete set of PPE recommended for contact with COVID-19 patients.
Long-Term Care Facilities
    Long-term care facilities include nursing homes, skilled nursing
facilities, and assisted living facilities. They provide both medical
and personal care services to people unable to live independently.
Because long-term care facilities are a congregate living situation,
infections such as COVID-19 can spread rapidly between patients or
residents and the healthcare staff who care for them. Therefore,
employees who work at these facilities have an elevated risk of
exposure and infection. Like employees who work at hospitals, employees
who work at long-term care facilities include both healthcare
practitioners, who may have direct and close contact with patients and
residents, as well as healthcare support staff who could also be
exposed to patients and residents. See the section on ``Detection of
SARS-CoV-2 in Healthcare Employees'' above for a description of the
types of employees who may work at these facilities.
    McMichael et al., (March 27, 2020) investigated a COVID-19 outbreak
affecting patients, employees, and visitors at a long-term care
facility in King County, Washington in February of 2020. SARS-CoV-2
infections were identified in 129 persons, including 81 residents, 34
of 170 staff (20%), and 14 visitors. None of the employees died, but 2
of the 34 infected employees (5.9%) had symptoms severe enough to
require hospitalization. The median age of the employees was 42.5 years
(range 22-79 years). Job titles reported for the employees that were
infected included physical therapist, occupational therapist assistant,
environmental care worker, nurse, certified nursing assistant, health
information officer, physician, and case manager. The study authors
noted that infection prevention procedures at the facility were
insufficient, and they concluded that introduction of SARS-CoV-2 into
long-term care facilities will result in high attack rates among
residents, staff, and visitors.
    Weil et al., (September 1, 2020) reported a cross-sectional study
of skilled nursing facilities in the Seattle area between March 29 and
May 13, 2020. Testing was performed by Public Health of Seattle and
King County (testing of both residents and staff) or the Seattle Flu
Study (testing of only employees). The authors described the period of
the study to be at the peak of the pandemic, but the skilled nursing
facilities were not experiencing outbreaks at the time of the study.
Testing of employees for SARS-CoV-2 was voluntary, and 1,583 employees
at 16 skilled nursing facilities were tested. Eleven of the 16 skilled
nursing facilities had at least one resident or employee who tested
positive. Forty-six (2.9%) employees had positive or inconclusive
testing for SARS-CoV-2. Of 1208 residents tested, 110 (9.1%) were
positive. Study authors noted shortages in PPE.
    Yi et al., (September 7, 2020) evaluated surveillance data on
COVID-19 for assisted living facilities in 39 states (representing 44%
of the total long-term care facilities in the U.S.). The states began
reporting data at various periods ranging from February 27 to April 30,
2020. As of October 15, 2020, 6,440 of 28,623 (22%) assisted living
facilities had at least one COVID-19 case among residents or staff
(ranging from 1.3% of assisted living facilities in Iowa to 92.8% of
assisted living facilities in Connecticut). In 22 states, 17,799 cases
of COVID-19 were reported in staff (total number of staff not
specified). In 9 states, 46 of 7,128 (0.6%) employees with COVID-19
died.
    Bagchi et al., (2021) reported on the CDC's National Healthcare
Safety Network (NHSN) surveillance of nursing homes, which began on
April 26, 2020. As of May 25, 2020, the Centers for Medicare & Medicaid
Services (CMS) began requiring nursing homes to report COVID-19 cases
in residents and staff. The authors analyzed data in residents, nursing
home staff, and facility personnel that was reported from May 25
through November 22, 2020 in all 50 states, the District of Columbia,
Guam, and Puerto Rico. Staff members and facility personnel were
defined as ``all persons working or volunteering in the facility,
including contractors,

temporary staff members, resident caregivers, and staff members who
might work at multiple facilities.'' The study authors reported that
``case count data were aggregated weekly, and resident-weeks were
calculated as the total number of occupied beds on the day data were
reported.'' Data on number of staff members employed were not
collected, and therefore ``resident weeks'' was used as ``a closest
best estimate of the at-risk denominator for staff members.'' The study
authors indicated that ``cases per 1,000 resident-week were calculated
for residents and staff members using the number of COVID-19 cases
reported in a week over the corresponding 1,000 resident-weeks.''
COVID-19 cases in staff members increased during June and July (10.9
cases per 1,000 resident-weeks reported in the week of July 26);
declined during August and September (6.3 per 1,000 resident-weeks in
the week of September 13); and increased again by late November (21.3
cases per 1,000 resident-weeks in the week of November 22). The study
authors noted that COVID-19 rates among nursing home staff followed
similar trends in nursing home residents and the surrounding
communities, thereby indicating a possible association between COVID-19
rates in nursing homes and nearby communities.
    Terebuh et al., (September 20, 2020) investigated COVID-19 clusters
in 45 congregate living facilities in Ohio, from March 7 to May 15,
2020. Most of the facilities investigated were healthcare worksites.
More than half of the clusters occurred at medical facilities (51% at
nursing homes, 11% at assisted living facilities, 7% at treatment
facilities, and 2% at intermediate care facilities). The remaining
clusters occurred at corrections facilities (7%), group homes (20%),
and shelters (2%). Of the combined 598 residents and healthcare
employees who were either confirmed to have COVID-19 or identified as a
probable case based on symptoms and close contact with a confirmed
case, healthcare employees represented 167 (28%) of the confirmed and
37 (6%) of the probable cases of COVID-19. None of the healthcare
employees died. The study authors were able to identify the index case
in 25 of the clusters, and 88% of the index cases were determined to be
healthcare employees.
Studies Focusing on Healthcare Support Services
    Healthcare support services employees, such as personnel that
provide food, laundry, or waste-handling services, are at risk of
exposure to patients with SARS-CoV-2 and contracting COVID-19.
Employees who provide healthcare support services usually have less
direct contact with patients, but they can have close contact with
COVID-19 patients or contaminated materials when performing tasks such
as cleaning patient rooms, removing waste or dirty laundry from patient
rooms, delivering food and picking up used food trays and utensils, or
repairing equipment in the patient's room. In addition, healthcare
support employees can have close and prolonged contact with their co-
workers while performing their duties.
    One study discussed above (Sims et al., November 5, 2020), shows an
infection rate among healthcare support services employees that is
similar to healthcare employees, such as physicians, who have some
patient contact. As noted, support personnel such as facilities/
security and administrative support employees had seropositivity rates
of approximately 7% to 8%, which were similar to rates in physicians
(values estimated from Figure 2B). Both healthcare support employees
and physicians had seropositivity rates that were higher than the rates
among employees working from home.
    Hale and Dayot (2020) examined an outbreak of COVID-19 among food
service employees that occurred in an academic medical center before
masking and physical distancing requirements were implemented. After an
employee in the food and nutrition department tested positive, 280
asymptomatic staff were tested. The entire food and nutrition
department that was actively working was considered exposed because
employees shared a common locker room and break area. Therefore,
testing was not limited to employees who worked near the index case as
part of their duties. Ten staff members in the department (including
the index case) tested positive during the investigation. At least
seven of the cases were thought to result from transmission from the
index case.
    Outbreaks for support services have not been well documented and
may be encapsulated with incidents for the entire hospital. Local
newspaper reports have identified potential incidents in laundry
facilities that handle linens contaminated with SARS-CoV-2. In a New
Jersey unionized laundry facility, representatives noted that eight
employees had been infected with SARS-CoV-2 and demanded improvements
in infectious disease control implementation (Davalos, December 21,
2020). In Canada, a Regina hospital laundry plant was connected with an
18-employee outbreak (Martin, August 10, 2020). The cause of the
outbreak was not determined.
Emergency Medical Services (EMS)
    A limited number of studies have examined the impact of COVID-19 on
employees who provide EMS (e.g., EMTs, paramedics), who are considered
healthcare personnel under this standard. The studies that address EMS
often address personnel such as EMTs along with other types of
emergency responders such as firefighters, who are not considered
healthcare personnel under this standard. EMTs and similar occupations,
such as paramedics, have close contact with patients who are or could
be infected with SARS-CoV-2 when they provide medical care or transport
those patients. The medical care they provide includes intubation and
cardiopulmonary resuscitation, which could generate aerosols and put
them at particularly high risk when performing those procedures on
someone with confirmed or suspected COVID-19.
    Prezant et al., (2020) reviewed paid medical leave data for EMS
providers and firefighters using New York City fire department
electronic medical records from October 1, 2017 through May 31, 2020.
The study authors found that as of May 31, 2020, 1,792 of 4,408 EMS
providers (40.7%) had been on leave for suspected or confirmed COVID-
19. When compared with the medical leave data from before the
pandemic--including months during influenza periods in prior years--the
authors found that medical leave for EMS providers was 6.8% above
baseline in March 2020 and peaked at 19.3% above baseline in April
2020. The authors determined that COVID-19 was responsible for this
increase. The medical leave levels for EMS providers were above those
for firefighters. Among firefighters, the data showed that 34.5% had
been on leave for suspected or confirmed COVID-19 as of May 31, 2020,
and there was a peak in medical leave at 13.0% above baseline in April
2020. A total of 66 (1.2%) firefighters and EMS providers with COVID-19
were hospitalized and 4 died. Despite EMS providers having been given
the same PPE (not further specified) as firefighters, EMS providers had
higher rates of COVID-19. The study authors concluded that higher rates
in EMS providers were attributable to greater exposure to COVID-19
patients while administering medical care.
    Weiden et al., (January 25, 2021) investigated risk factors for
SARS-CoV-2 infection and severe disease (hospitalization or death) in
New York City first responders (EMS and

firefighters) from March 1 through May 31, 2020, based on medical
records. The study had a total of 14,290 participants (3,501 EMS
personnel and 10,789 firefighters). From March 1 to May 31, 2020, 9,115
(63.8%) responders had no COVID-19 diagnosis, 5,175 (36.2%) were
confirmed or suspected COVID-19 cases, and 62 (0.4%) were hospitalized.
Three participants died in a hospital, and one died at home.
Researchers found that EMS respondents had more cases of severe COVID-
19 than firefighters (42/3501 [1.2%] vs. 21/10,789 [0.19%]). The SARS-
CoV-2 infection rate among New York City first responders overall was
15 times the New York City rate. EMS personnel had a 4-fold greater
risk of severe disease and 26% increased risk of confirmed COVID-19
cases when compared with firefighters. Both firefighters and EMS
personnel responded to the pandemic-related emergency medical calls and
followed the same PPE protocols. However, EMS personnel had greater
COVID-19 exposure than firefighters due to greater COVID-19-related
call volume and being solely responsible for patient transport,
nebulization of bronchodilators, and intubation.
    Tarabichi et al., (October 30, 2020) recruited first responders
(from EMS and fire departments) to participate in a study in the
Cleveland, Ohio area. The authors conducted a first serologic survey
and virus test in the period between April 20 through May 19, 2020 and
a second between May 18 and June 2, 2020. A total of 296 respondents
completed a first visit and 260 completed the second visit. Seventy-one
percent of respondents reported exposure to SARS-CoV-2 and 16 (5.4%)
had positive serological testing. No subject had a positive virus test.
Fifty percent (8/16) of those who tested positive were either
asymptomatic or mildly symptomatic. Based on responses to questions
about suspected contacts (it does not appear that the time period of
exposure was considered), the study author concluded that likely
sources of transmission in participants who tested positive were
patients or co-workers.
    In a study examining COVID-19 antibodies in employees from public
service agencies in the New York City area from May through July of
2020, 22.5% of participants were found to have COVID-19 antibodies
(Sami et al., March 2021). The percentages of EMTs and paramedics found
to have antibodies (38.3 and 31.1%) were among the highest levels
observed in all the occupations. The study authors noted that risk of
exposures may be increased for employees who provide emergency medical
services because those services are provided in uncontrolled,
unpredictable environments, where space is limited (e.g., ambulances)
and quick decisions must often be made. Both emergency technicians and
paramedics perform procedures such as airway management that involve a
high risk of exposure. In fact, the proportions of employees who had
antibodies were found to be increased with increasing frequency of
aerosol-generating procedures.
In-Home Healthcare Providers
    In-home healthcare workers provide medical or personal care
services, similar to those provided in long-term care facilities,
inside the homes of people unable to live independently. Patients
receiving in-home care could receive services from different types of
healthcare providers (e.g., a nurse administering medical care, a
physical therapist assisting with exercise, a personal care services
provider assisting with daily functions such as bathing). In addition,
a number of workers may provide services to the same patient, while
working in shifts over the course of the day. In-home healthcare
providers have a high risk of infection from working close to patients
and possibly their family members or other caregivers in enclosed
spaces (e.g., performing a physical examination, helping the patient
bathe).
    The impact of COVID-19 on in-home healthcare workers is not well
studied. In-home healthcare workers might be included in reports of
COVID-19 cases and deaths in healthcare workers, but those reports do
not indicate if any of the affected healthcare workers provided home
care. One report from the UK indicated that an occupational category of
``social care'' which included ``care workers and home carers''
experienced significantly increased rates of death involving COVID-19
(50.1 deaths per 100,000 men and 19.1 deaths per 100,000 women) from
March through May of 2020 (Windsor-Shellard et al., June 26, 2020). And
in a related study from March through December of 2020, it was reported
that nearly three in four deaths involving COVID-19 in social care
operations were in ``care workers and home carers,'' with 109.9 deaths
per 100,000 men and 47.1 deaths per 100,000 women (Windsor-Shellard et
al., January 25, 2021).
Conclusion
    The representative studies OSHA described in this section on
healthcare provide examples of the pervasive impact that SARS-CoV-2
exposures have had on employees in those industries before vaccines
were available. Even since vaccines have become widely available,
approximately 20 to 30% of healthcare workers remained unvaccinated as
of March 2021 (King et al., April 24, 2021), and breakthrough cases
among vaccinated healthcare employees are evident. The evidence is
consistent with OSHA's determination that SARS-CoV-2 poses a grave
danger to healthcare employees. Cases or outbreaks in settings such as
hospitals, long-term care facilities, and emergency services
departments have had a clear impact on employees in those types of
workplaces. The evidence establishes that employees in those settings,
whether they provide direct patient care or supporting services, have
been infected with SARS-CoV-2 and have developed COVID-19. Some of
these employees have died and others have become seriously ill.
Employees in healthcare are at elevated risk for transmission in the
workplace. Employees in these industry settings are exposed to these
forms of transmission through in-person interaction with patients and
co-workers in settings where individuals with suspected or confirmed
COVID-19 receive care. In many cases, close contact with people who are
suspected or confirmed to have COVID-19 is required of personnel in
these types of workplaces, and such close contact usually occurs
indoors. These employees, who form the backbone of the nation's medical
response to the COVID-19 public health emergency, clearly require
protection under this ETS.
References
Bagchi, S et al., (2021). Rates of COVID-19 among residents and
staff members in nursing homes--United States, May 25-November 22,
2020. MMWR 70: 52-55. http://dx.doi.org/10.15585/mmwr.mm7002e2.
(Bagchi et al., 2021).
Barrett, ES et al., (2020). Prevalence of SARS-CoV-2 infection in
previously undiagnosed health care workers in New Jersey, at the
onset of the US COVID-19 pandemic. BMC infectious diseases 20(1): 1-
0. doi: 10.1101/2<IP_ADDRESS>72470. (Barrett et al., 2020).
Burrer, SL et al., (2020). Characteristics of health care personnel
with COVID-19--United States, February 12-April 9, 2020. MMWR
69(15): 477-481. https://www.cdc.gov/mmwr/volumes/69/wr/mm6915e6.htm. (Burrer et al., 2020).
Carter, RE et al., (2021, March 26). Prevalence of SARS-CoV-2
Antibodies in a Multistate Academic Medical Center. Mayo Clin Proc.
2021 May; 96(5): 1165-1174. doi: 10.1016/j.mayocp.2021. 03.015.
PMID: 33958053; PMCID:

PMC7997730. (Carter et al., March 26, 2021).