[1] Univ Calif Los Angeles, Fielding Sch Publ Hlth, Dept Epidmiol, 615 E Charles Young Dr S, Los Angeles, CA 90095 USA
[2] Univ Cape Town, Sch Publ Hlth & Family Med, Div Epidemiol & Biostat, Cape Town, South Africa
[3] Univ Cape Town, Sch Publ Hlth & Family Med, Div Social & Behav Sci, Cape Town, South Africa
[4] Univ Western Cape, Sch Publ Hlth, Bellville, South Africa
[5] Univ Cape Town, Desmond Tutu Hlth Fdn, Cape Town, South Africa
[6] Univ Calif Los Angeles, David Geffen Sch Med, Div Infect Dis, Los Angeles, CA 90095 USA