Antiretroviral medication and HIV prevention: new steps forward and new questions

During the past 2 years, several pivotal clinical trials have proven that the use of antiretrovirals by HIV-infected and at-risk uninfected persons can decrease the probability of HIV being transmitted sexually. The initial chemoprophylaxis studies evaluated tenofovir administered topically or orally (with or without emtricitabine). However, several questions remain. Some subsequent primary prevention studies did not replicate the results of the initial studies, raising questions about differences in the behaviors of participants in each study (in particular about medication adherence), as well as whether pharmacologic or local mucosal factors might explain the variable efficacy estimates. Other antiretrovirals and delivery systems are being evaluated to maximize the efficacy of primary chemoprophylactic approaches. At present, increasing access to antiretroviral treatment globally is a priority, because expanding access to medication that can prevent morbidity and mortality is itself an important public health goal and may reasonably be expected to decrease HIV incidence. However, for treatment as prevention to be maximally effective, increases in HIV testing, health care workers, and infrastructure are needed, in addition to medications and laboratory support for clinical monitoring. A combination of approaches is needed to most quickly decrease the current trends in HIV incidence, including early diagnosis and initiation of treatment for HIV-infected persons. These approaches can be coupled with appropriately tailored interventions for populations at greatest risk for infection (for example, men who have sex with men and sex workers), including male circumcision, behavioral interventions, and chemoprophylaxis. However, a substantial gap exists between current expenditures and unmet needs, which suggests that mobilization of political will is needed for this combination approach to be successful.