[1] Univ Witwatersrand, Fac Hlth Sci, Perinatal HIV Res Unit PHRU, Johannesburg, South Africa
[2] Univ Witwatersrand, Ctr Hlth Policy, Sch Publ Hlth, Johannesburg, South Africa
[3] BC Childrens Hosp Res Inst, Vaccine Evaluat Ctr, Vancouver, BC, Canada
[4] Univ Calif San Diego, Ctr Gender Equ & Hlth, Sch Med, La Jolla, CA USA
[5] Simon Fraser Univ, Fac Hlth Sci, Blusson Hall Rm 10522,8888 Univ Dr, Burnaby, BC V5A 1S6, Canada
[6] Univ Witwatersrand, Fac Hlth Sci, Dept Obstet & Gynaecol, MRU MatCH Res Unit, Durban, South Africa
[7] Univ Paul Sabatier, Univ Toulouse, Ctr Epidemiol & Res POPulat Hlth CERPOP, Inserm, Toulouse, France
[8] South African Med Res Council, Hlth Syst Res Unit, Bellville, South Africa
[9] African Social Sci Unit Res & Evaluat ASSURE, Div Wits Hlth Consortium, Johannesburg, South Africa
[10] Womens Hlth Res Inst, Vancouver, BC, Canada
[11] Harvard Med Sch, Brigham & Womens Hosp, Dept Med, Div Pharmacoepidemiol & Pharmacoecon, Boston, MA USA