[1] South African Med Res Council, Cochrane South Africa, Cape Town, South Africa
[2] Stellenbosch Univ, Fac Med & Hlth Sci, Dept Global Hlth, Div Epidemiol & Biostat, Cape Town, South Africa
[3] Bayero Univ, Aminu Kano Teaching Hosp, Dept Community Med, Kano, Nigeria
[4] WHO Reg Off Africa, Vaccine Preventable Dis Programme, Brazzaville, Rep Congo