The study will enroll HIV-uninfected MSM at risk for acquiring HIV infection. Participants will be enrolled over 2 years and followed up until the closure of the clinical study. Therefore, the follow up duration will be up to 3 years for first enrollees and up to1 year for the last enrollee. The study will be implemented in Thailand (60% of participants) and France (40%).~Participants will be randomly assigned to one of two regimens:~Experimental Arm (F/TAF): one tablet of the fixed-dose combination of emtricitabine (FTC) 200 mg + tenofovir alafenamide (TAF) 25mg, 2 to 24 hours before sexual intercourse followed by a second tablet 24 hours after the first intake.~Control Arm (F/TDF): two tablets of the fixed-dose combination of emtricitabine (FTC) 200 mg + tenofovir disoproxil fumarate (TDF) 300 mg, 2 to 24 hours before sexual intercourse followed by a third tablet 24 hours after the first drug intake and a fourth tablet 24 hours later.~Participants will attend up to 15 study visits throughout the study. Visits may include physical examinations, blood collection, urine collection, and swabs collection (oral and rectal). At the end of their study participation, all participants will be transitioned to locally available HIV prevention services, including PrEP.
The purpose of this study is to evaluate the efficacy, acceptability, and safety of a simplified event-driven pre-exposure prophylaxis of HIV based on oral TAF/FTC in HIV-uninfected cisgender men who have sex with men (MSM).~Primary objective: To assess the efficacy of emtricitabine 200 mg + tenofovir alafenamide 25 mg (F/TAF), taken 2 to 24 hours before sexual intercourse followed by a second dose 24 hours after the first intake, in reducing the risk of HIV acquisition in MSM relative to the background HIV incidence rate.