Background Antiretroviral chemoprophylaxis before exposure is a promising approach for
the prevention of human immunodeficiency virus (HIV) acquisition. Methods We randomly
assigned 2499 HIV-seronegative men or transgender women who have sex with men to
receive a combination of two oral antiretroviral drugs, emtricitabine and tenofovir disoproxil
fumarate (FTC–TDF), or placebo once daily. All subjects received HIV testing, risk-reduction
counseling, condoms, and management of sexually transmitted infections. Results The study …