[1] Anova Hlth Inst, 12 Sherborne Rd, ZA-2193 Johannesburg, South Africa
[2] Boston Univ, Sch Publ Hlth, Dept Global Hlth, Boston, MA USA
[3] Univ Witwatersrand, Fac Hlth Sci, Hlth Econ & Epidemiol Res Off, Johannesburg, South Africa
[4] Univ Cape Town, Southern Africa Labour & Dev Res Unit, Cape Town, South Africa
[5] Univ Penn, Sch Nursing, Dept Family & Community Hlth, Philadelphia, PA USA
[6] Univ Penn, Perelman Sch Med, Dept Med Eth & Hlth Policy, Philadelphia, PA USA
[7] Univ Witwatersrand, Sch Publ Hlth, Fac Hlth Sci, Dept Community Hlth, Johannesburg, South Africa