LAUSR

Recent studies among men who have sex with men suggest that sexual behaviors associated with risk of sexually transmitted infections increase following initiation of pre-exposure prophylaxis (PrEP) for HIV prevention. We used longitudinal data from HIV-uninfected participants (n = 1013) enrolled in an open-label study of PrEP delivered to Ugandan and Kenyan heterosexual HIV serodiscordant couples to understand the association between PrEP initiation and HIV risk-related sexual behaviors among these couples. In the month following PrEP initiation, the mean number of monthly sex acts within couples decreased from 7.9 to 6.9 (mean difference: − 1.1; 95% CI − 1.5, − 0.7) and the proportion of couples having condomless sex decreased from 65% to 32% (percentage point change: − 33%; 95% CI − 37%, − 30%); these behaviors then remained relatively constant over 2 years. We found no evidence of sexual risk compensation following PrEP initiation within African serodiscordant couples. However, roughly a third of couples continued to engage in condomless sex during follow up, emphasizing the importance of continued PrEP use to sustain HIV protection.