1. Wits Reproductive Health and HIV Institute, University of the Witwatersrand, Johannesburg, South Africa
2. School of Clinical Medicine, Faculty of Medicine, University of the Witwatersrand, Johannesburg, South Africa
3. Clinical Microbiology and Infectious Diseases, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
4. Centre for Evidence-Based Intervention, Department of Social Policy and Intervention, University of Oxford, Oxford, UK
5. Department of Population, Reproductive and Family Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, USA