Doravirine (DOR) in Human Immunodeficiency Virus (HIV)-Infected Children Aged 4 Weeks to <12 Years and <45 kg (MK-1439-066)

This is a single-group, open-label, multi-site study in pediatric participants with human immunodeficiency virus type 1 (HIV-1) infection, aged 4 weeks to \<12 years and weighing \<45 kg, who are treatment-naive (TN) or have been virologically suppressed (VS) on stable combination antiretroviral therapy (cART) for ≥3 months with no history of treatment failure. The primary objectives are:

* To evaluate the steady state pharmacokinetics (PK) of doravirine (DOR) \[MK-1439\] when given in combination with 2 nucleoside/nucleotide analog reverse transcriptase inhibitors (NRTIs) or as part of the fixed-dose combination (FDC) of DOR/lamivudine (3TC)/tenofovir disproxil fumarate (TDF) in participants ≥6 to \<12 years and weighing ≥14 to \<45 kg. * To evaluate the safety and tolerability of DOR when given with 2 NRTIs or as part of the FDC of DOR/3TC/TDF, in participants ≥6 to 12 years and weighing ≥14 to \<45 kg, through Week 24.