Merck & Co. has initiated Phase 3 studies of MK-8527, an investigational once-monthly oral pill for HIV pre-exposure prophylaxis (PrEP). Trials will enroll populations at elevated risk of HIV-1 exposure across 16 countries, including sub-Saharan Africa, where a second study will recruit women and adolescent girls with Gates Foundation support. This development complements existing PrEP options, with the goal of providing a convenient, long-acting oral alternative to daily pills and twice-yearly injectables. The trial launch follows regulatory momentum around Gilead’s twice-yearly injectable PrEP, Yeztugo.