amfAR, The Foundation for AIDS Research

When One Partner Is Positive: Early Antiretroviral Therapy Prevents HIV Infection in Discordant Couples


October 2011 - HIV sero-discordance is a term that describes when one sexual partner is HIV-positive while the other partner is HIV-negative. Adding to a growing body of research on the use of HIV treatment for prevention, a large clinical trial called HPTN 052 found that early initiation of antiretroviral therapy (ART) can reduce the risk of HIV transmission in sero-discordant couples.1.

A total of 1,763 couples from nine countries were enrolled in the study. Ninety-seven percent were heterosexual, 61 percent were between 26 and 40 years old, and 30 percent were from India or Thailand. Half of the HIV-positive partners—all of whom had CD4 levels of 350 to 550 cells/mm3—were immediately started on antiretroviral therapy, while the other half delayed until their CD4 levels dropped to 250 cells/ mm3 or they developed an AIDS-related illness.

During the study, four of the HIV-negative partners in the early treatment group became infected, compared to 34 partners in the delayed group. After taking the follow-up periods for all of the couples into consideration, this meant that an HIV-negative partner in the early treatment group had about one-tenth the risk of experiencing HIV transmission compared to someone in the delayed treatment group. The researchers also found that the HIV-positive partners who started treatment early had an almost 40 percent reduction in the number of clinical events (e.g., opportunistic infections) associated with HIV disease progression.

This study showed that starting antiretroviral therapy at higher CD4 levels can benefit both the HIV-positive and HIV-negative partner, providing strong scientific evidence for the benefits of treatment as prevention for sero-discordant heterosexual couples. Although early treatment may not be feasible or appropriate in all situations, these results have added to an ongoing debate over whether international treatment guidelines should be changed to maximize the potential preventive and clinical benefits of antiretroviral therapy.

1. Cohen MS, et al. Prevention of HIV-1 infection with early antiretroviral therapy. N Engl J Med. 2011 Aug 11;365(6):493-505. Epub 2011 Jul 18.