[1] Univ Cape Town, Dept Med, Div Clin Pharmacol, Cape Town, South Africa
[2] Univ Cape Town, Sch Publ Hlth & Family Med, Ctr Infect Dis Epidemiol & Res, Cape Town, South Africa
[3] Univ Witwatersrand, Rahima Moosa Mother & Child Hosp, Sch Clin Med,Fac Hlth Sci, Dept Paediat & Child Hlth,Empilweni Serv & Res Un, Johannesburg, South Africa
[4] Univ Cape Town, Dept Paediat & Child Hlth, Cape Town, South Africa
[5] Univ Cape Town, Dept Paediat & Child Hlth, Div Neonatol, Cape Town, South Africa