1. Africa Health Research Institute, Durban, South Africa
2. School of Nursing and Public Health, University of KwaZulu-Natal, South Africa
3. Centre for the AIDS Programme of Research in South Africa (CAPRISA), University of KwaZulu-Natal, Durban, South Africa
4. Institute of Epidemiology and Health Care, University College London, London, UK
5. Department of Global Health and Population, Harvard T.H. Chan School of Public Health, Boston, MA, USA
6. Institute for Public Health, University of Heidelberg, Heidelberg, Germany
7. Department of Statistics, Department of Biobehavioral Nursing and Health Informatics, Center for Statistics and the Social Sciences and Center for Studies in Demography and Ecology, University of Washington, Seattle, WA, USA