Women’s estimated HIV infections from sex in trials of pre-exposure prophylaxis in Africa: Implications for HIV prevention strategies

Introduction: During 2004-15, nine randomized controlled trials (RCT) for HIV prevention tested pre-exposure prophylaxis (PrEP) with oral drugs, vaginal gels, or vaginal rings among more than 17,000 women in Africa. Methods: This study uses information from the nine RCTs to estimate the proportions of HIV from sexual and bloodborne risks, to consider reasons for success or failure with oral PrEP, and to consider risks with vaginal PrEP. Results: Estimating from women’s reported frequencies of unprotected coital acts in six RCTs, only a minority of women’s infections came from sex. Oral PrEP may have succeeded in at least one trial by reducing infections from both bloodborne and sexual risks. Oral PrEP may have failed in several trials, at least in part, because some women used oral PrEP when they had sexual risks rather than daily as advised. Relatively high incidence with PrEP vaginal gels and rings vs. oral placebo suggests vaginal PrEP had little impact at best and may have been harmful. Discussion: Evidence from this and other studies challenges the common belief most HIV in Africa comes from sex. This challenge has implications for HIV prevention strategies, including: warning about bloodborne risks; and reconsidering PrEP for young women.