Use of tenofovir and abacavir for initial and subsequent regimens in HIV treatment. Abacavir (ABC) or tenofovir alafenamide (TAF) + lamivudine (3TC) or emtricitabine (FTC) is the suggested nucleoside reverse transcriptase inhibitor (NRTI) backbone for subsequent ART in children < 30 kg. This includes children previously treated with ABC or zidovudine (AZT)