Study of Doravirine/Islatravir (DOR/ISL 100 mg/0.75 mg) to Evaluate the Antiretroviral Activity, Safety, and Tolerability in Treatment-Naïve Participants With Human Immunodeficiency Virus Type 1 (HIV-1) Infection (MK-8591A-020)

Inclusion Criteria:

• Is human immunodeficiency virus type 1 (HIV-1) positive

• Is naïve to antiretroviral therapy (ART) defined as having received ≤10 days ofprior therapy with any antiretroviral agent following a diagnosis of HIV-1 infectionincluding prevention of mother-to-child transmission up to 1 month prior toscreening.

• A female participant is eligible to participate if she is not pregnant orbreastfeeding, and at least one of the following conditions applies: 1) Is not awoman of childbearing potential (WOCBP); 2) Is a WOCBP and using an acceptablecontraceptive method, or be abstinent from heterosexual intercourse as theirpreferred and usual lifestyle (abstinent on a long term and persistent basis); 3) AWOCBP must have a negative highly sensitive pregnancy test ([urine or serum] asrequired by local regulations) within 24 hours before the first dose of studyintervention; 4) If a urine test cannot be confirmed as negative (eg, an ambiguousresult), a serum pregnancy test is required

Exclusion Criteria:

• Has HIV-2 infection

• Has hypersensitivity or other contraindication to any of the components of the studyinterventions as determined by the investigator

• Has an active diagnosis of hepatitis due to any cause, including active HBVinfection (defined as hepatitis B surface antigen [HBsAg]-positive or hepatitis Bvirus deoxyribonucleic acid [HBV DNA]-positive)

• Has a history of malignancy ≤5 years prior to signing informed consent except foradequately treated basal cell or squamous cell skin cancer, in situ cervical cancer,or cutaneous Kaposi's sarcoma

• Has a history or current evidence of any condition (including active tuberculosisinfection), therapy, laboratory abnormality or other circumstance (including drug oralcohol use or dependence) that might, in the opinion of the investigator, confoundthe results of the study or interfere with the participant's participation for thefull duration of the study

• Has been treated for a viral infection other than HIV-1, such as hepatitis B, withan agent that is active against HIV-1

• Is taking or is anticipated to require systemic immunosuppressive therapy, immunemodulators, or any prohibited therapy from 45 days prior to Day 1 through the studyintervention period

• Is currently participating in or has participated in a clinical study with aninvestigational compound or device from 45 days prior to Day 1 through the studyintervention period

• Has a documented or known virologic resistance to any approved HIV-1 reversetranscriptase inhibitor, or any study intervention

• Has exclusionary laboratory values within 45 days prior to Day 1

• Is female and is expecting to conceive or donate eggs at any time during the study