[1] Univ Cape Town, Sch Publ Hlth, Observ, Falmouth Rd, ZA-7925 Cape Town, South Africa
[2] Univ Cape Town, Sch Publ Hlth & Family Med, Cape Town, South Africa
[3] Sarraounia Publ Hlth Trust, Johannesburg, South Africa
[4] Univ Western Cape, South African Bioinformat Inst, Life Sci Bldg, Bellville, South Africa
[5] Sarraounia Publ Hlth Trust, Johannesburg, South Africa
[6] Stellenbosch Univ, Fac Med & Hlth Sci, Dept Paediat & Child Hlth, Worcester, South Africa
[7] Univ Cape Town, Sch Publ Hlth, Cape Town, South Africa
[8] Univ Witwatersrand, Ctr Hlth Policy, Sch Publ Hlth, Johannesburg, South Africa
[9] Warwick Med Sch, Warwick, England
[10] Univ Witwatersrand, Ctr Hlth Policy, Sch Publ Hlth, Johannesburg, South Africa
[11] Univ Witwatersrand, Fac Hlth Sci, Maternal & Child Hlth, Wits RHI, Johannesburg, South Africa
[12] Johns Hopkins Sch Publ Hlth, Baltimore, MD USA
[13] Univ Witwatersrand, Sch Sociol, Johannesburg, South Africa