Antiretroviral prophylaxis: a defining moment in HIV control.

A defi ning moment in the global AIDS response has been reached. The discourse is no longer about HIV prevention or HIV treatment; it is now about HIV control through the implementation of antiretrovirals as key components of combination interventions. Barely a year ago, visions of HIV control would have been considered far-fetched. The impetus for this change in mindset, which has been building since the XVIII International AIDS Conference in Vienna last year, emanates from the compelling evidence that antiretroviral drugs prevent HIV infection in the general heterosexual population, which is released this week and presented at the 6th International AIDS Society Conference on HIV Pathogenesis, Treatment and Prevention in Rome by the Partners PrEP 1 and Botswana TDF2 2 trials. The Partners PrEP trial, 1 involving 4758 HIV discordant couples from Kenya and Uganda, found that daily oral tenofovir disoproxil fumarate (TDF) and TDF-emtricitabine reduced HIV transmission by 62% and 73%, respectively. The Bostwana TDF2 trial, 2 in 1200 heterosexual men and women from the general population, found that daily oral TDF-emtricitabine reduced HIV transmission by 63%. These fi ndings follow close on the heels of the CAPRISA 004 trial 3 of tenofovir gel, the iPrEX trial 4 of oral TDF-emtricitabine in men who have sex with men, and the HPTN 052 trial 5 of early antiretroviral treatment as HIV prevention. Importantly, these new fi ndings fi ll a critical gap in HIV prevention with a readily available antiretroviral approach to prevent heterosexual transmission in both men and women (fi gure). Women benefi t from a new prevention option under their control, which is particularly important for those not assured of their partner's fi delity or willingness to use a condom. The hope these studies add to HIV prevention is further bolstered by the recent step taken by the pharmaceutical company Gilead Sciences Inc to lodge TDF and emtricitabine with the UNITAID patent pool, 12 thus enabling lower cost versions of the drugs to be manufactured and thereby facilitating wider access in poor countries. There is now no doubt that antiretroviral drugs prevent HIV infection. However, important scientifi c questions remain. Does the inclusion of emtricitabine in pre-exposure prophylaxis (PrEP) formulations provide suffi cient additional benefi t to warrant the additional costs and side-eff ects? Are levels of eff ectiveness and safety similar for daily use and use-with-sex of PrEP? Do the safety, eff ectiveness, cost, and acceptability