[1] Univ KwaZulu Natal, Nelson R Mandela Sch Med, Doris Duke Med Res Inst, CAPRISA, ZA-4013 Durban, South Africa
[2] Columbia Univ, Dept Epidemiol, Mailman Sch Publ Hlth, New York, NY USA
[3] Columbia Univ, Int Ctr AIDS Care & Treatment Programs ICAP, Mailman Sch Publ Hlth, New York, NY USA
[4] Yale Univ, Sch Med, Dept Internal Med & Epidemiol, New Haven, CT USA