Antiretroviral therapy (ART) for HIV infection provides lasting protection against the sexual transmission of the virus from infected men and women to their HIV-uninfected sexual partners. The discovery, made by investigators from the University of North Carolina at Chapel Hill and the HIV Prevention Trials Network (HPTN), was reported July 20 at the eighth International AIDS Society (IAS) Conference on HIV Pathogenesis, Treatment and Prevention in Vancouver, Canada.
[Photo: “The HPTN 052 trial was designed to address two questions — whether providing antiretroviral therapy to an HIV-infected person would prevent HIV transmission to a sexual partner, and whether earlier antiretroviral therapy offered long-lasting health benefits,” said UNC’s Dr. Myron Cohen (left). “The answer to both is a resounding ‘yes.’” Photo by Mr. Dan Sears]
Dr. Myron Cohen, professor of epidemiology at UNC’s Gillings School of Global Public Health and director of UNC’s Institute for Global Health and Infectious Diseases, was principal investigator for the study, known as HPTN 052. Dr. Cohen is also Yeargan-Bate Eminent Distinguished Professor of Medicine, Microbiology and Immunology.
HPTN 052 began in 2005 and enrolled 1,763 HIV sero-discordant couples – i.e., one member of the couple is HIV-infected, and the other is not – at 13 sites in nine countries. Ninety-seven percent of the couples were heterosexual. HIV-infected partners were assigned either to initiate ART at the beginning of the study, called the “early” arm, or later in the study, called the “delayed” arm. Those on the delayed arm started ART when their bodies’ immune systems were declining.
“These findings demonstrate that antiretroviral therapy, when taken until viral suppression is achieved and sustained, is a highly effective, durable intervention for HIV prevention,” Dr. Cohen said. “The HPTN 052 trial was designed to address two questions — whether providing antiretroviral therapy to an HIV-infected person would prevent HIV transmission to a sexual partner, and whether earlier antiretroviral therapy offered long-lasting health benefits. The answer to both is a resounding ‘yes.’”
In 2011, an interim review of the study data showed a 96 percent reduction of HIV transmission within the couples assigned to early ART, which was considered a major breakthrough finding. After the release of the results, all participants in the delayed ART arm were offered the opportunity to begin ART, and the study continued for four more years.
By the end of the study, 1,171 couples remained in follow-up.
As reported July 20 at the IAS conference, the final results show a sustained 93 percent reduction of HIV transmission within couples when the HIV-infected partner was taking ART as prescribed and viral load was suppressed. Notably, there were only eight cases of HIV transmission within couples after the HIV-infected partner was given ART. However, four of these eight cases were diagnosed soon after ART initiation, and transmission likely occurred before the HIV-infected partner was virally suppressed.