1. Clinical Epidemiology Division, Department of Medicine, Solna, Karolinska Institutet, Stockholm, Sweden
2. Department of Global Health Policy, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
3. Centre for Population Research in Sexual Health and HIV, Institute for Global Health, University College London, London, United Kingdom
4. Department of Medicine, Washington University School of Medicine, St Louis, Missouri
5. Center for Sexual Health Promotion, School of Public Health, Indiana University, Bloomington