New HIV Resistance to Antiretrovirals Almost Disappears in Switzerland

September 2016

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What the Results Mean for You

All of the trends summarized in the preceding section reflect the impact of the stronger antiretrovirals that became available after 1999. The strength of these new antiretrovirals against resistant HIV -- and the variety of different antiretrovirals available -- mean chances of controlling HIV infection have improved over the years. As a result, fewer people are getting AIDS illnesses. Controlling HIV also helps prevent or control some major non-AIDS diseases.

In the Swiss study participants, this lower risk of AIDS and non-AIDS diseases has improved survival with HIV over the years. Proportions of people who died from AIDS fell from 4% in people who started antiretrovirals before 1999, to 2.4% in people who started therapy in 1999-2006, and to 0.5% in people who started in 2007-2013 (Figure 2). Proportions of people who died from any cause in those three periods fell from 18.6% to 10.3% to 2.1%.

AIDS and All-Cause Death Rates by Year of Starting Antiretrovirals

AIDS and All-Cause Death Rates by Year of Starting Antiretrovirals

Figure 2. Among people who started antiretroviral therapy in Switzerland, those who started in more recent years had much lower rates of death due to AIDS and to all causes. (Credit: Teresa B. Southwell)

Do resistance findings like these in Switzerland reflect what's happening in other countries, including the United States? Switzerland differs from the United States in one important aspect of HIV care: Everyone in Switzerland receives free HIV care and free antiretroviral therapy. Some HIV-positive people in the United States still have no health insurance or poor insurance, and that impairs their access to antiretrovirals and care. But the antiretrovirals available and HIV treatment guidelines are very similar in the United States and Switzerland. A study in the United States tracked a drop in resistance among antiretroviral-treated people from 1999 through 2008.3 And a 1997-2008 study in 7 countries across Western Europe made similar findings.4


There are two keys to avoiding resistance when taking antiretroviral therapy. First, everyone should have a resistance test before starting therapy to see if they have been infected with virus already resistant to some antiretrovirals. If a person has resistance before starting therapy, the HIV provider can pick an antiretroviral combination that should control that resistant virus. Second, once a person starts a well-selected antiretroviral combination, quickly reaching and maintaining an undetectable viral load will prevent resistant HIV from developing. Reaching and keeping an undetectable viral load depend on taking all your antiretrovirals every day exactly as your provider instructs.

For almost everyone living with HIV today in the United States, Switzerland, and countries with similar HIV epidemics, providers can find an antiretroviral combination that will control HIV -- even if that person's HIV already carries resistance mutations. Taking those antiretrovirals regularly is essential to reaching an undetectable viral load, preventing resistance mutations from developing, and living a long and productive life.


  1. Scherrer AU, von Wyl V, Yang WL, et al. Emergence of acquired HIV-1 drug resistance almost stopped in Switzerland: a 15-year prospective cohort analysis. Clin Infect Dis. 2016;62:1310-1317.
  2. AIDSinfo. Fact sheets. HIV treatment. Drug resistance. 2016.
  3. Buchacz K, Baker R, Ward DJ, et al. Trends in decline of antiretroviral resistance among ARV-experienced patients in the HIV Outpatient Study: 1999-2008. AIDS Res Treat. 2012;2012:230290.
  4. De Luca A, Dunn D, Zazzi M, et al. Declining prevalence of HIV-1 drug resistance in antiretroviral treatment-exposed individuals in Western Europe. J Infect Dis. 2013;207:1216-1220.
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