Antiretroviral medications that are used as prophylaxis can prevent acquisition of
human immunodeficiency virus type 1 (HIV-1) infection. However, in clinical trials
among African women, the incidence of HIV-1 infection was not reduced, probably
because of low adherence.Longer-acting methods of drug delivery, such as vaginal
rings, may simplify use of antiretroviral medications and provide HIV-1 protection.