Purpose of review: Preexposure prophylaxis (PrEP), in which HIV uninfected persons with ongoing HIV risk use oral antiretroviral medications as chemoprophylaxis against sexual HIV acquisition, is a promising new HIV prevention strategy.
Recent findings: During the past 2 years, proof-of-concept that PrEP protects against sexual HIV acquisition has been demonstrated in three clinical trials, conducted among MSM and heterosexual men and women. These trials used daily oral tenofovir disoproxil fumarate, alone or coformulated with emtricitabine. The degree of HIV protection in these trials was strongly related to the level of adherence to PrEP. Two additional clinical trials, both among heterosexual women, did not demonstrate HIV protection with PrEP, with low adherence to daily use of PrEP the leading hypothesis for lack of efficacy; adherence and biologic mechanisms for lack of efficacy in these trial populations are being evaluated.
Summary: Oral chemoprophylaxis, using tenofovir and combination emtricitabine–tenofovir, is effective for prevention of sexual HIV transmission. Next steps in the field include rigorous evaluation of uptake and adherence to PrEP in implementation settings.