1. Department of Pediatrics & Child Health, Red Cross War Memorial Children's Hospital, and SA MRC Unit on Child & Adolescent Health, University of Cape Town, Cape Town, South Africa;
2. Department of Paediatrics and Child Health, Tygerberg Hospital, Stellenbosch University, Cape Town, South Africa;
3. Division of Cardiology, Department of Medicine, Groote Schuur Hospital and Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa;
4. Division of Epidemiology & Biostatistics, School of Public Health & Family Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa; and
5. Division of Infectious Diseases, Department of Pediatrics, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL.