[1] Univ Cape Town, Inst Infect Dis & Mol Med, Desmond Tutu HIV Ctr, ZA-7705 Cape Town, South Africa
[2] Univ Cape Town, Sch Publ Hlth & Family Med, Infect Dis Epidemiol Unit, ZA-7925 Cape Town, South Africa
[3] Columbia Univ, Mailman Sch Publ Hlth, Dept Epidemiol, New York, NY USA
[4] Univ Cape Town, Dept Med, ZA-7925 Cape Town, South Africa