1 Stellenbosch Institute for Advanced Study, Wallenberg Research Centre at Stellenbosch University, Stellenbosch 7600, South Africa; MRC/Wits Rural Public Health and Health Transitions Research Unit, School of Public Health, University of the Witwatersrand, Johannesburg, South Africa; School of Population Sciences and Health Services Research, Faculty of Life Sciences and Medicine, King's College London, London, UK. Electronic address: justine.davies@kcl.ac.uk.
2 Stellenbosch Institute for Advanced Study, Wallenberg Research Centre at Stellenbosch University, Stellenbosch 7600, South Africa; Department of Paediatrics, University of British Columbia, Vancouver, BC, Canada.
3 Stellenbosch Institute for Advanced Study, Wallenberg Research Centre at Stellenbosch University, Stellenbosch 7600, South Africa; MRC/Wits Rural Public Health and Health Transitions Research Unit, School of Public Health, University of the Witwatersrand, Johannesburg, South Africa; Umeå Centre for Global Health research, Umeå University, Umeå, Sweden.
4 Stellenbosch Institute for Advanced Study, Wallenberg Research Centre at Stellenbosch University, Stellenbosch 7600, South Africa; MRC Developmental Pathways for Health Research Unit, Department of Paediatrics, School of Public Health, University of the Witwatersrand, Johannesburg, South Africa.
5 Stellenbosch Institute for Advanced Study, Wallenberg Research Centre at Stellenbosch University, Stellenbosch 7600, South Africa; London school of Hygiene and Tropical Medicine, London, UK; MRC/UVRI Uganda Research Unit, Entebbe, Uganda.
6 Stellenbosch Institute for Advanced Study, Wallenberg Research Centre at Stellenbosch University, Stellenbosch 7600, South Africa; Great Ormond Street Hospital, Institute of Child Health, University College London, London, UK.
7 Stellenbosch Institute for Advanced Study, Wallenberg Research Centre at Stellenbosch University, Stellenbosch 7600, South Africa; Faculty of Medicine and Biomedical Sciences, University of Yaoundé I, Yaoundé, Cameroon.
8 Stellenbosch Institute for Advanced Study, Wallenberg Research Centre at Stellenbosch University, Stellenbosch 7600, South Africa; Dalla Lana School of Public Health and Department of Surgery, University of Toronto, ON, Canada.