[1] Univ British Columbia, Fac Med, Vancouver, BC, Canada
[2] British Columbia Womens Hosp, Womens Hlth Res Inst, Vancouver, BC, Canada
[3] Univ British Columbia, Dept Obstet & Gynaecol, Vancouver, BC, Canada
[4] London Sch Hyg & Trop Med, Fac Publ Hlth & Policy, London, England
[5] Univ British Columbia, Dept Pathol & Lab Med, Vancouver, BC, Canada
[6] British Columbia Womens Hosp, Oak Tree Clin, Vancouver, BC, Canada
[7] British Columbia Ctr Excellence HIV AIDS, Vancouver, BC, Canada
[8] Univ British Columbia, Dept Med, Div Aids, Vancouver, BC, Canada
[9] Univ British Columbia, Dept Pediat, Div Infect & Immunol Dis, Vancouver, BC, Canada
[10] Univ British Columbia, Dept Med, Div Infect Dis, Vancouver, BC, Canada