The goal of this study is to evaluate the efficacy of the study drugs, lenacapavir (LEN) and emtricitabine/tenofovir alafenamide (F/TAF) in preventing HIV infection, in adolescent girls and young women (AGYW). The primary objective of this study is to evaluate the efficacy of LEN and F/TAF for HIV-1 PrEP in AGYW at risk of HIV-1 infection.