Oral Islatravir (MK-8591) Once-Monthly as Preexposure Prophylaxis (PrEP) in Men and Transgender Women Who Have Sex With Men and Are at High Risk for HIV-1 Infection (MK-8591-024)

The main purpose of the study is to evaluate the efficacy and safety of oral Islatravir (ISL) once monthly (QM) as Preexposure Prophylaxis (PrEP) in cisgender men who have sex with men (MSM) and transgender women (TGW) who have sex with men and who are at high risk of HIV-1 infection with a minimum follow-up of 48 weeks and at least 50% of participants have 96 weeks of follow-up after randomization. The primary hypothesis of the study is that the administration of ISL QM as PreP reduces the incidence rate per year of the confirmed HIV-1 infections compared to the background incidence rates.