Pre-Exposure Prophylaxis Study of Lenacapavir and Emtricitabine/Tenofovir Alafenamide in Adolescent Girls and Young Women at Risk of HIV Infection

Key Inclusion Criteria: * Incidence Phase * HIV-1 status unknown at initial screening and no prior human immunodeficiency virus (HIV)-1 testing within the last 3 months. * Sexually active (has had \> 1 vaginal intercourse within the last 3 months) with cisgender male individuals (CGM). * Randomized Phase * Negative fourth generation HIV-1 antibody (Ab)/antigen (Ag) test confirmed with central HIV-1 testing. * Estimated glomerular filtration rate (GFR) ≥ 60 mL/min at screening. * Body weight ≥ 35 kg. Key Exclusion Criteria: * Prior receipt of an HIV vaccine. * Prior use of any long-acting systemic HIV pre-exposure prophylaxis (PrEP) or prior HIV postexposure prophylaxis (PEP) in the past 12 weeks. Note: Other protocol defined Inclusion/Exclusion criteria may apply.