[1] South African Med Res Council, Hlth Syst Res Unit, POB 19070, ZA-7505 Cape Town, South Africa
[2] Univ Cape Town, Div Child & Adolescent Psychiat, Dept Psychiat & Mental Hlth, Adolescent Hlth Res Unit, 46 Sawkins Rd, ZA-7700 Cape Town, South Africa
[3] Univ Cape Town, Div Social & Behav Sci, Sch Publ Hlth & Family Med, Cape Town, South Africa
[4] Univ Witwatersrand, Sch Clin Med, Perinatal HIV Res Unit, Fac Hlth Sci, Johannesburg, South Africa
[5] South African Med Res Council, Off AIDS & TB Res, POB 19070, ZA-7505 Cape Town, South Africa
[6] Univ Pretoria, Dept Internal Med, Pretoria, South Africa