Preventing HIV-1 infection is a high global priority. This study assessed prevention strategies in young women in South Africa, Uganda, and Zimbabwe using oral or vaginal antiretroviral agents. No approach was found to be effective. The HIV-1 incidence was 5.7 per 100 person-years. Daily oral preexposure prophylaxis with 300 mg of tenofovir disoproxil fumarate (TDF), alone or in combination with 200 mg of emtricitabine (FTC) (TDF-FTC Truvada, Gilead Sciences), reduces the risk of acquisition of human immunodeficiency virus type 1 (HIV-1) by 50% or more among persons with high adherence to the regimen, with demonstrated efficacy in men who have sex with men, heterosexuals, and injection-drug users. 1 – 4 On the basis of these observations, in July 2012 the Food and Drug Administration approved daily treatment with Truvada for the prevention of HIV-1 acquisition, and the Centers for Disease Control and Prevention has issued . . .