1. Washington University School of Medicine, St Louis, Missouri, USA
2. Global HIV, Hepatitis and STI Programme, World Health Organization, Geneva, Switzerland
3. Department of Public Health, Environments and Society, London School of Hygiene & Tropical Medicine, London, United Kingdom
4. Department of Epidemiology, University of California, San Francisco, California, USA
5. Department of Global Health and Development, London School of Hygiene and Tropical Medicine, London, United Kingdom
6. Department of Epidemiology, John Hopkins School of Public Health, Baltimore, Maryland, USA