1. Paediatric Unit, King Edward VIII Hospital, Durban, South Africa
2. Department of Paediatrics and Child Health, Nelson R Mandela School of Medicine, University of KwaZulu-Natal, Durban, South Africa
3. School of Nursing and Public Health, College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
4. Department of Pediatrics, College of Physicians and Surgeons, Columbia University, New York, New York, USA
5. Department of Medicine, Division of Infectious Diseases, Columbia University, New York, New York, USA