A Study to Provide Continued Access to Study Drug to Children and Adolescents Who Have Completed Clinical Studies Involving Gilead HIV Treatments

The goal of this clinical study is to provide continued access to the study drug(s) to children and adolescents with human immunodeficiency virus type 1 (HIV-1) who completed their participation in an applicable parent study and to monitor for adverse events. The primary objectives of this study are as follows: * To provide continued access to the study drug received in the parent protocol or switch to bictegravir/emtricitabine/tenofovir (B/F/TAF) for participants who completed a Gilead parent study evaluating drugs for HIV treatment. * To evaluate the safety of the study drug(s) in participants with HIV-1.

Key Inclusion Criteria: * Completed an applicable parent study: GS-US-292-0106, GS-US-380-1474, GS-US-311-1269, or GS-US-216-0128, and gave consent to study participation. Key Exclusion Criteria: * Individuals planning to switch to B/F/TAF on Day 1 with plasma HIV RNA ≥ 50 copies/mL during the last parent study visit prior to screening/Day 1 visit. * Note: individuals planning to switch after Day 1 must not have plasma HIV RNA ≥ 50 copies/mL (or detectable HIV-1 RNA level according to the local assay being used if the limit of detection is ≥ 50 copies/mL). * Individuals planning to switch to B/F/TAF with any ongoing Grade 3 or 4 drug-related AE or clinically relevant Grade 3 or 4 drug-related laboratory abnormality (confirmed on repeat) related to any component of B/F/TAF prior to treatment switch. * For those on B/F/TAF or planning to switch to B/F/TAF: previous treatment discontinuation of any component of B/F/TAF due to toxicity or intolerance. * For those planning to switch to B/F/TAF: known hypersensitivity to any component of the study drug, its metabolites, or formulation excipients. * Ongoing treatment with or prior use of any prohibited medications. Note: Other protocol defined Inclusion/Exclusion criteria may apply.