Appendix 2—Glossary

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Air changes:

Ratio of the volume of air flowing through a space in a certain period of time (air flow rate) to the volume of that space (room volume);usually expressed as the number of room air changes per hour (ACH).

Airborne infection isolation room (AIIR):

Single- occupancy patient-care room in which environmental factors are controlled to minimize transmission of infectious agents spread from person to person by droplet nuclei associated with coughing or aerosolization of contaminated fluids;AIIRs typically have specific requirements for controlled ventilation, air pressure, and air filtration.

Airborne infection isolation precautions:

Measures to reduce the risk of airborne transmission of infectious agents; an AIIR with negative pressure relative to the surrounding area is required for full implementation.

Airborne transmission:

Occurs by dissemination of either airborne droplet nuclei (small-particle residue [5 µm or smaller] of evaporated droplets containing microorganisms that remain suspended in the air for long periods of time) or dust particles containing the infectious agent. Microorganisms carried in this manner can be dispersed widely by air currents and may become inhaled by a susceptible host in the same room or over a longer distance from the source patient, depending on environmental factors.


Procedure for visually examining the respiratory tract and/or obtaining specimens for diagnostic purposes; requires inserting an instrument (bronchoscope) through a patient’s mouth or nose into the trachea.

Close contact:

A person who has cared for or lived with a person with SARS or had a high likelihood of direct contact with respiratory secretions and/or body fluids of a person with SARS either during the period the person was clinically ill or within 10 days of resolution of symptoms. Examples of close contact include kissing or embracing, sharing eating or drinking utensils, talking within 3 feet, physical examination, and any other direct physical contact between persons. Close contact does not include activities such as walking by a person or briefly sitting across a waiting room or office.

Community containment:

Measures to separate infected or exposed persons by use of isolation, quarantine, or other restrictions on movement and activities ;isolation and quarantine are common practices in public health, and both aim to control exposure to infected or potentially infected persons; both may be used voluntarily or compelled by public health authorities.

Community transmission:

In the context of SARS, transmission of SARS-CoV outside of well-defined settings (i.e., hospitals; households of SARS patients).


A person who has been exposed to someone with a communicable disease during the infectious period. (See “close contact.”)

Contact precautions:

Work practices to reduce the risk of transmitting infectious agents by direct or indirect contact with an infectious person.

Contact tracing:

Identification and location of persons who may have been exposed to a person with SARS-CoV infection ;may result in regular monitoring for evidence of illness and strict or modified quarantine.



Droplet precautions:

Measures to reduce the risk of droplet transmission of infectious agents.

Droplet transmission:

Occurs when droplets containing infectious agents are propelled a short distance through the air (e.g., by coughing, sneezing, or talking) and deposited in the eyes, nose or mouth of a susceptible person.


Condition of being subjected to something (e.g., an infectious agent) that could have a harmful effect.

Fit test:

The use of a protocol to qualitatively or quantitatively evaluate the fit of a respirator on an individual to assess the adequacy of fit of that respirator brand/model on that individual.

Hand hygiene:

A general term that applies to any one of the following: 1) handwashing with plan (non-antimicrobial) soap and water, 2) antiseptic handwash (soap containing antiseptic agents and water), 3) antiseptic hand rub (waterless antiseptic product, most often alcohol-based, rubbed on surfaces of hands), or 4) surgical hand antisepsis.

Healthcare worker:

Any employee in a healthcare facility who has close contact with patients, patient-care areas, or patient-care items; also referred to as “healthcare personnel.”

High-efficiency particulate air (HEPA) filter:

Type of air filter that removes >99.97% of particles 0.3 um or larger at a specified flow rate of air.

Incident command system:

Predetermined organizational structure for potential mass casualty events that address planning, operations, logistics, finance, and administration.

Incubation period:

Time interval between infection (i.e., introduction of the infectious agent into the susceptible host) and the onset of the first symptom of illness known to be caused by the infectious agent.

Infection control:

Measures practiced by healthcare personnel in healthcare facilities to decrease transmission and acquisition of infectious agents (e.g., proper hand hygiene, scrupulous work practices, use of personal protective equipment (PPE) [masks or respirators, gloves, gowns, and eye protection]; infection control measures are based on how an infectious agent is transmitted and include standard, contact, droplet, and airborne precautions.


Separation of an ill person who has a communicable disease (e.g., SARSpatient) from those who are healthy. Isolation prevents transmission of infection to others and also allows for the focused delivery of specialized health care to ill persons.


Watching, keeping track of, or checking for a specific purpose. In the context of SARS, monitoring refers to assessment (by phone or in person) of a person who has a known or possible exposure to SARS-CoV to detect the development of symptoms and ensure prompt implementation of precautions if necessary.

  • Passive monitoring:
    relies on self-assessment by the affected person, who is asked to contact health authorities if symptoms develop.
  • Active monitoring: involves direct assessment of each affected person at least once a day by healthcare or public health staff or designee.

N-95 respirator:

Respirator whose filtering efficiency has been determined to be at least 95% for the most penetrating sized particle (~0.3 um); an N-95 respirator may either be a disposable filtering facepiece respirator (the entire face piece serves as the filter) or an elastomeric facepiece respirator equipped with an appropriate particulate filter cartridge.

Negative pressure:

Pressure less than that of the ambient atmosphere.


Acquired in a healthcare setting or as a result of medical care.

PCR (polymerase chain reaction):

Laboratory method for detecting the genetic material of an infectious disease agent in specimens.

Personal protective equipment (PPE):

Specialized clothing and equipment designed to create a barrier against health and safety hazards; examples include goggles, face shields, gloves, and respirators.

Powered air-purifying respirator (PAPR):

Respirator equipped with a face piece, hood, or helmet, breathing tube, air-purifying filter, cartridge and/or canister, and fan; air is pulled through the air-purifying element and pushed through the breathing tube and into the face piece, hood, or helmet.


Separation or restriction of activities of well persons who are not ill but who are believed to have been exposed to a communicable disease and are therefore at high risk of becoming infected. In the context of SARS, quarantine refers to a combined approach to managing contacts, which consists of active monitoring plus activity restrictions.


A personal protective device that is worn over the nose and mouth to reduce the risk of inhaling hazardous airborne particles, gases, or vapors.

Respiratory hygiene/cough etiquette:

A group of infection control measures used to contain infection at its source by covering the mouth and nose during coughing and sneezing, using tissues to contain respiratory secretions with prompt disposal in a no-touch receptacle, and maintaining spatial separation when coughing. These measures are targeted to patients and the persons accompanying them beginning at the point of initial encounter with a healthcare setting.

Respiratory symptoms:

When screening patients for potential SARS-CoV disease, “respiratory symptoms” generally refers to symptoms of infection of the lower respiratory tract (e.g., cough, shortness of breath, difficulty breathing). However, when screening patients who have a high risk of exposure to SARS-CoV (e.g., persons previously identified through contact tracing or self-identified as close contacts of a laboratory-confirmed case of SARS-CoV disease; persons who are epidemiologically linked to a laboratory-confirmed case of SARS-CoV disease), respiratory symptoms used to screen patients should be expanded to include upper respiratory symptoms such as sore throat and rhinorrhea (in addition to other early non-respiratory symptoms of SARS-CoV disease such as subjective fever, chills, rigors, myalgia, headache, and diarrhea).


Severe acute respiratory syndrome; a clinical syndrome characterized by fever, lower respiratory symptoms, and radiographic evidence of pneumonia.


SARS-associated coronavirus; a newly described coronavirus that is genetically and antigenically distinct from other human coronaviruses.

SARS isolation precautions:

The combined use of Standard, Contact, and Droplet Precautions plus Airborne Infection Isolation for the care of SARS patients. This combination of isolation precautions is recommended until the dynamics of SARS-CoV transmission are more fully defined.


Four-fold or greater increase in antibody titer between acute- and convalescent-phase serum specimens tested in parallel, or negative antibody test on acute-phase serum with positive test on convalescent-phase serum tested in parallel.

Serologic assay:

A laboratory method for detecting the presence and/or level of antibodies to an infectious agent in serum from a person. Antibodies are substances made by the body’s immune system to fight a specific infection.

Snow-day measure:

One type of community containment measure designed to prevent transmission of a communicable disease by limiting social interactions and preventing inadvertent exposures. Community members are asked to stay home as they would during a major snowstorm. Schools are closed, work sites are closed or restricted, large public gatherings are cancelled, and public transportation is halted or scaled back.

Standard Precautions:

Work practices required for the basic level of infection control; they center on proper hand hygiene and also include use of protective barriers and appropriate handling of clinical waste.

Surge capacity:

Ability to obtain additional resources when needed during an emergency.


Any mechanism through which an infectious agent, such as a virus, is spread from a reservoir or source to a human.

Travel advisory:

One type of notification of an outbreak of disease occurring in a geographic area. A travel advisory provides information about the disease outbreak and informs travelers how to reduce their risk of acquiring the infection. An advisory recommends against nonessential travel to the area.

Travel alert:

One type of notification of an outbreak of disease occurring in a geographic area. A travel alert provides information about the disease outbreak and informs travelers how to reduce their risk of acquiring the infection. An alert does not include a recommendation against nonessential travel to the area.


The process for sorting or “ranking” ill or injured people into groups based on their need for or benefit from immediate medical treatment.

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