1. Division of Epidemiology & Biostatistics; School of Public Health & Family Medicine; University of Cape Town; Cape Town South Africa
2. Anova Health Institute; Johannesburg South Africa
3. Division of Medical Virology; University of Cape Town & National Health Laboratory Services; Cape Town South Africa
4. Department of Obstetrics & Gynaecology; University of Cape Town; Cape Town South Africa
5. ICAP; Columbia University Mailman School of Public Health; New York NY USA
6. Desmond Tutu HIV Centre; Institute of Infectious Diseases & Molecular Medicine; University of Cape Town; Cape Town South Africa
7. College of Physicians & Surgeons; Columbia University; New York NY USA