A Study of Islatravir (ISL) and Ulonivirine (ULO) Once Weekly (QW) in Virologically Suppressed Adults With Human Immunodeficiency Virus Type 1 (HIV-1) (MK-8591B-060)

Investigators are trying to find better treatments for people with HIV-1. In this clinical study, investigators want to see how well a new treatment called ISL+ULO, taken once a week, works compared to an existing treatment called BIC/FTC/TAF, which is taken every day. Investigators will check how many people still have a high level of the virus in their blood after 24 weeks. The investigators also want to understand if the new treatment, MK-8591B, is safe and how well people can handle it.

Inclusion: The main inclusion criteria include but are not limited to the following: \- Has been receiving Bictegravir/Emtricitabine/Tenofovir alafenamide (BIC/FTC/TAF) therapy with documented viral suppression \[Human immunodeficiency virus type 1 (HIV-1) ribonucleic acid (RNA) \<50 copies/mL\] for ≥6 months prior to providing documented informed consent and has no history of prior virologic treatment failure on any past or current regimen. Exclusion: The main exclusion criteria include but are not limited to the following: * Has Human immunodeficiency virus type 2 (HIV-2) infection. * Has a diagnosis of an active Acquired immune deficiency syndrome (AIDS)-defining opportunistic infection. * Has active hepatitis C virus (HCV) coinfection. * Has hepatitis B virus (HBV) coinfection. * Has a history of malignancy ≤5 years prior to providing documented informed consent except for adequately treated basal cell or squamous cell skin cancer, in situ cervical or in situ anal cancer, or cutaneous Kaposi's sarcoma. * Has prior exposure to Islatravir (ISL) or Ulonivirine (ULO) for any duration any time prior to Day 1.