1. HIV Prevention Research Unit, South African Medical Research Council, KwaZulu-Natal, South Africa
2. Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, United Kingdom
3. Department of Global Health, School of Medicine, University of Washington, Seattle
4. Biostatistics Unit, South African Medical Research Council, Durban, KwaZulu-Natal, South Africa
5. The Kirby Institute, University of New South Wales, Kensington, Australia