1. School of Public Health Building, University of the Witwatersrand, (Education Campus), 27 St Andrew's Road, Parktown, Johannesburg, South Africa
2. Division of Health Policy and Systems, School of Public Health and Family Medicine, Faculty of Health Sciences, University of Cape Town, Anzio Road, Observatory, Cape Town, South Africa
3. Department of Global Health and Development, Faculty of Public Health and Policy, London School of Hygiene and Tropical Medicine, Keppel Street, London, UK