1. Division of Clinical Epidemiology, Department of Clinical Research, University Hospital Basel , Basel , Switzerland
2. Department of HIV, Hepatitis, and Sexually Transmitted Infections, World Health Organization , Geneva , Switzerland
3. Centre for Infectious Disease Epidemiology and Research, School of Public Health and Family Medicine, Faculty of Health Sciences, University of Cape Town , Cape Town , South Africa
4. Health Economics and Epidemiology Research Office, Faculty of Health Sciences, University of the Witwatersrand , Johannesburg , South Africa
5. Department of Global Health, Boston University School of Public Health , Boston, Massachusetts , USA