Incidence Phase - CGM, TGW, TGM, and GNB who have condomless receptive anal sex with partners assigned male at birth and are at risk for HIV infection. - HIV-1 status unknown at screening and no prior HIV-1 testing within the last 3 months - Sexually active with ≥ 1 partner assigned male at birth (condomless receptive anal sex) in the last 12 months and 1 of the following: - Condomless receptive anal sex with ≥ 2 partners in the last 12 weeks - History of syphilis, rectal gonorrhea, or rectal chlamydia in the last 24 weeks - Self-reported use of stimulants with sex in the last 12 weeks Randomized Phase - Negative local rapid fourth generation HIV-1/2 Ab/Ag, central fourth generation HIV-1/2 Ab/Ag, and HIV-1 RNA quantitative nucleic acid amplification testing (NAAT) - Estimated glomerular filtration rate (eGFR) ≥ 60 mL/min at screening according to the Cockcroft-Gault formula for creatinine clearance (CLcr)

Incidence Phase - Prior use of oral PrEP (including F/TDF or F/TAF) in the past 12 weeks or any prior use of long-acting systemic PrEP (including cabotegravir or islatravir) - Prior recipient of an HIV vaccine or HIV broadly neutralizing antibody formulation Randomized Phase - Acute viral hepatitis A, B or C or evidence of chronic hepatitis B or C infection - Severe hepatic impairment or a history of or current clinical decompensated liver cirrhosis Note: Other protocol defined Inclusion/Exclusion criteria may apply.