Taking HIV "Treatment is Prevention" to New Heights

Somewhat missing from the headlines in recent days is a landmark HIV study the solidifies the concept that treatment is prevention. The back story to that important catch phrase is that, in the recent past, there was a real policy debate over where emphasis should be placed: on treatment or on prevention. One's answer to that question would have multiple cascading effects on which anti-HIV strategies were planned, evaluated, and promoted. 

All that changed with the publication of HPTN 052 which demonstrated a 96% reduction in sexual transmission of HIV in mostly hetorosexual serodiscordant couples when the HIV-infected member was on HIV therapy. This trial was revolutionary in that it showed that the HIV treatment vs. prevention debate rested on a false dichotomy. Its results changed the way HIV prevention was viewed and provided yet another reason to initative therapy as soon as possible in the HIV infected. Caveats to the generalizability of this study existed however and included the high number of heterosexual couples and a high use of condoms (94%). Despite these caveats, HPTN 052 was pathbreaking.

Buttressing and expanding HPTN 025 is the PARTNER study, recently published in JAMA. This study's aim was to assess the ability of antiretroviral therapy on the transmission of HIV in serodiscordant couples who regularly engaged in condomless sex. The results, which solidify the treatment as prevention, paradigm are stunning.

The trial included about 2/3 heterosexual couples and 1/3 men-who-have-sex with men (MSM) couples. Condom-less sex occurred between couples a median of 37 times per year. Strikingly, just 11 transmission events occurred with nearly 60,000 condom-less sex acts. The thing about the 11 HIV infections was they were not genetically linked to the other study partner, meaning these infections derived from an additional partner not in the study--a great example of the exception proving the rule. 

This study shows just how potent antiretroviral therapy is. It is not only life-saving for those who take it but extremely effective at extinguishing contagiousness. As we wait for a vaccine, antiretroviral therapy (treatment as well as pre-exposure prophylaxis) is the cornerstone to keeping HIV contained.