1. The Desmond Tutu HIV Centre, Institute for Infectious Disease and Molecular Medicine, Faculty of Health Science, University of Cape Town, Cape Town, South Africa.
2. Department of Epidemiology, Fielding School of Public Health, University of California Los Angeles, Los Angeles, California, USA.
3. Division of Epidemiology and Biostatistics, School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa.
4. Medical Ethics and Health Policy, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, Pennsylvania, USA.
5. Center for Health Incentives and Behavioral Economics, Medical Ethics and Health Policy, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, Pennsylvania, USA.
6. Matchboxology, Kalk Bay, Cape Town, South Africa.
7. Division of Men's Health, Desmond Tutu HIV Centre, University of Cape Town, South Africa.
8. Department of Psychiatry, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, Pennsylvania, USA.
9. Department of Family and Community Health, School of Nursing, University of Pennsylvania, Philadelphia, Pennsylvania, USA.