1. Department of EpidemiologyColumbia University Mailman School of Public Health New York NY USA
2. Division of Epidemiology and Biostatistics, School of Public HealthUniversity of the Witwatersrand Johannesburg South Africa
3. School of Nursing and Public HealthUniversity of KwaZulu‐Natal Durban South Africa
4. HIV Center for Clinical and Behavioral Studies at Columbia University and New York State Psychiatric Institute New York NY USA
5. Department of Pediatrics, College of Physicians & SurgeonsColumbia University New York NY USA