Introduction Antiretroviral pre-exposure prophylaxis (PrEP) reduces the incidence of acquisition of human immunodeficiency virus type 1 (HIV-1) in men who have sex with men and is a promising approach for preventing HIV-1 in heterosexual populations. Methods We conducted a randomized, three-arm trial of oral antiretroviral PrEP among heterosexual couples from Kenya and Uganda in which one member was HIV-1 seronegative and the other HIV-1 seropositive. Seronegative partners were randomly assigned to once-daily tenofovir (TDF), combination emtricitabine/tenofovir (FTC/TDF), or matching placebo and followed monthly for up to 36 months. At enrollment, HIV-1 seropositive partners were not eligible for antiretroviral therapy under national guidelines. All couples received standard HIV-1 treatment and prevention services, including individual and couples risk-reduction counseling and condoms. Results 4758 couples were enrolled; for 62%, the HIV-1 seronegative partner was male. For HIV-1 seropositive participants, the median CD4 count was 495 cells/μL (interquartile range 375–662). Of 82 post-randomization HIV-1 infections, 17 were among those assigned TDF (incidence 0.65 per 100 person-years), 13 among those assigned FTC/TDF (incidence 0.50 per 100 person-years), and 52 among those assigned placebo (incidence 1.99 per 100 person-years), indicating a 67% relative reduction in HIV-1 incidence for TDF (95% CI 44 to 81, p<0.001) and 75% for FTC/TDF (95% CI 55 to 87, p<0.001). HIV-1 protective effects of FTC/TDF and TDF were not significantly different (p=0.23), and both study medications significantly reduced HIV-1 incidence in both men and women. The rate of serious medical events was similar across the study arms. Conclusions Oral TDF and FTC/TDF provided substantial protection against HIV-1 acquisition in heterosexual men and women, with comparable efficacy of TDF and FTC/TDF. (Funded by the Bill and Melinda Gates Foundation; ClinicalTrials.gov number NCT00557245)

Background-High plasma HIV-1 RNA concentrations are associated with increased risk of HIV-1 transmission. Initiation of antiretroviral therapy (ART) reduces plasma HIV-1 concentrations, but little empiric data are available on the rate of sexual HIV-1 transmission from persons receiving ART.