HIV Control Through Treatment Durably Prevents Heterosexual Transmission of Virus
NIH-Funded Trial Proves Suppressive Antiretroviral Therapy for HIV-infected People Effective in Protecting Uninfected Partners
July 20, 2015 - Antiretroviral treatment that consistently suppresses HIV is highly
effective at preventing sexual transmission of the virus in heterosexual couples where one person is
HIV-infected and the other is not, investigators report today at the 8th International AIDS
Society Conference on HIV Pathogenesis, Treatment & Prevention (IAS 2015) in Vancouver,
Canada. The finding comes from the decade-long HPTN 052 clinical trial funded primarily by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, and conducted by the NIH-funded HIV Prevention Trials Network (HPTN).
In 2011, the HPTN 052 study investigators reported a breakthrough: Starting HIV treatment early,
when the immune system is relatively healthy, reduced the risk of sexually transmitting the virus
to an uninfected partner by 96 percent over 18 months. Based on additional data gathered since
2011, today’s finding unequivocally demonstrates the enduring power of HIV-controlling
antiretroviral therapy to greatly reduce sexual transmission of the virus.
“The study now makes crystal clear that when an HIV-infected person takes antiretroviral therapy
that keeps the virus suppressed, the treatment is highly effective at preventing sexual
transmission of HIV to an uninfected heterosexual partner,” said NIAID Director
Anthony S. Fauci, M.D. “For heterosexuals who can achieve and maintain viral
suppression, the risk to their partners is exceedingly low.”
The HPTN 052 trial was designed to evaluate whether antiretroviral therapy reduces sexual transmission
of HIV. Beginning in April 2005, the study enrolled 1,763 heterosexual couples ages 18 or older in
Botswana, Brazil, India, Kenya, Malawi, South Africa, Thailand, the United States and Zimbabwe.
Each couple included one partner with HIV infection and one without. Infected participants
were assigned at random either to start antiretroviral therapy right away, while their
immune system was relatively healthy, or to delay starting treatment until their
immune system weakened or they developed an AIDS-defining illness, consistent
with World Health Organization guidelines at the time. All participants
received condoms and counseling on how to protect their partners from sexual transmission of HIV.
Once the investigators reported their landmark data in 2011, all infected study participants were
offered the opportunity to begin antiretroviral therapy right away, and the trial continued for
another four years, concluding this spring. At the end of the study, 1,171 couples remained in the trial.
Investigators report today that starting antiretroviral therapy early reduced HIV transmission by
93 percent over the course of the study. Only eight cases of HIV transmission occurred in
uninfected partners of HIV-infected participants who received antiretroviral therapy.
Four of these infections were diagnosed shortly after the start of treatment. In
these cases, the virus most likely was transmitted just before antiretroviral
therapy began or right after it commenced, before treatment had fully
suppressed HIV replication. The other four infections occurred in
study participants for whom treatment no longer was working and
the virus was replicating. Treatment failure may have occurred
because HIV-infected participants did not take their
antiretroviral drugs as prescribed or had an HIV
strain that was resistant to one or more of the drugs in their treatment regimen.
The lack of sexual transmission of HIV by virally suppressed individuals in this large study provides
robust evidence that antiretroviral therapy started at any time in the course of infection can prevent
heterosexual HIV transmission if viral suppression is achieved and maintained, the investigators note.
“Throughout our decade-long study with more than 1,600 heterosexual couples, we did not observe HIV
transmission when the HIV-infected partner’s virus was stably suppressed by antiretroviral therapy,”
said Myron Cohen, M.D., the study’s principal investigator. Dr. Cohen is Associate Vice Chancellor
for Global Health at the University of North Carolina at Chapel Hill and director of the
university’s Institute for Global Health and Infectious Diseases. “These findings
illustrate that treatment is an incredibly powerful tool for HIV prevention.”
HPTN 052 investigators also are reporting findings today about relationships between viral load, viral
suppression, treatment failure and drug resistance. The researchers found that having a relatively high
level of HIV in the blood at the start of therapy was associated with a longer time to viral
suppression, which, in turn, was associated with both the occurrence of treatment failure
and a shorter time to treatment failure. Thus, having a relatively high viral load at
the start of treatment could increase the risk for HIV transmission, the scientists suggest.
In addition, the investigators found that among the HPTN 052 participants who started antiretroviral
therapy early but failed treatment before May 2011, those who had a higher viral load when they
joined the study were likely to develop resistance to their antiretroviral drugs. Additional
analysis is needed to clarify this association, according to the investigators.
For more information about the HPTN 052 trial, please see Questions and Answers: The HPTN 052 Study: Preventing Sexual Transmission of HIV with Anti-HIV Drugs. Information is also available in ClinicalTrials.gov under study identifier NCT00074581.
?M Cohen, et al . Final results of the HPTN 052 randomized controlled trial: antiretroviral therapy prevents HIV transmission. Program number MOAC0106LB, Track C.
SH Eshleman, et al . Treatment as prevention: characterization of partner infections in the HIV Prevention Trials Network 052 trial. Program number MOAC0106LB, Track C.
J Fogel, et al . Identification of factors associated with viral suppression and treatment failure when antiretroviral therapy is used for HIV prevention: results from the HIV Prevention Trials Network (HPTN 052) trial. Program number MOPEC417, Track C.
D Sabin, et al . Analysis of HIV drug resistance in adults receiving early antiretroviral treatment for HIV prevention: results from the HIV Prevention Trials Network (HPTN 052) trial. Program number TUPEB285, Track B.
NIAID conducts and supports research—at NIH, throughout the United States, and worldwide—to study the causes of infectious and immune-mediated diseases, and to develop better means of preventing, diagnosing and treating these illnesses. News releases, fact sheets and other NIAID-related materials are available on the NIAID website.
About the National Institutes of Health (NIH) : NIH, the nation's medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov.
Source: National Institute of Allergy and Infectious Diseases (NIAID) http://www.niaid.nih.gov/news/newsreleases/2015/Pages/HPTN052results.aspx
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