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