Randomized , open-label noninferiority trial conducted at Rahima Moosa Mother and Child Hospital , Johannesburg , South Africa , from June 2010 to December 2013 , enrolling 300 HIV-infected children exposed to nevirapine for prevention of mother-to-child transmission who were aged 3 years or older and had plasma HIV RNA of less than 50 copies/mL during ritonavir-boosted lopinavir-based therapy ; 298 were randomized and 292 ( 98 % ) were followed up to 48 weeks after randomization .