1. Africa Health Research Institute, KwaZulu-Natal, South Africa
2. Institute of Global Health, University College London, London, UK
3. Africa Health Research Institute, School of Nursing and Public Health, University of KwaZulu-Natal, Durban, South Africa
4. Faculty of Medicine and Faculty of Social, Human and Mathematical Sciences, Southampton University, Southampton, UK
5. Research Department of Epidemiology & Public Health, University College London, London, UK
6. London School of Hygiene & Tropical Medicine, London, UK
7. School of Public Health, University of the Witwatersrand, Johannesburg, South Africa