1. Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
2. Department of Epidemiology, Johns Hopkins School of Public Health, Baltimore, MD, USA
3. Witkoppen Health and Welfare Centre, Johannesburg, South Africa
4. Clinical HIV Research Unit, Department of Medicine, University of the Witwatersrand, Johannesburg, South Africa
5. Right to Care, Johannesburg, South Africa