NOTE B: Modifications of ART during the 24 weeks prior to study entry are permitted in certain circumstances. For example, the change in formulation (eg, from standard formulation to fixed-dose combination including ART modifications switching from ritonavir- to cobicistat-boosted protease inhibitors or from tenofovir disoproxil fumarate to tenofovir alafenamide) is allowed within 24 weeks prior to study entry. A within-class, single-drug substitution (eg, switch from nevirapine to efavirenz or from atazanavir to darunavir) is allowed within 24 weeks prior to study entry, with the exception of a switch between any other NRTI to/from abacavir. No other changes in ART within the 24 weeks prior to study entry are permitted.