1. Department of Paediatrics and Child Health, Tygerberg Hospital and Stellenbosch University, Cape Town, South Africa
2. Family Center for Research with Ubuntu (FAMCRU), Cape Town, South Africa
3. Perinatal HIV Research Unit, Chris Hani Baragwanath Academic Hospital, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
4. School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
5. Department of Medicine, University of California San Diego
6. Desmond Tutu HIV Centre, University of Cape Town, South Africa