1. 1Sydney Brenner Institute for Molecular Bioscience, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa; email: michele.ramsay@wits.ac.za
2. 2Malawi Epidemiology and Intervention Research Unit, Lilongwe, Malawi
3. 3Regional Institute for Population Studies, University of Ghana, Accra, Ghana
4. 4African Population and Health Research Center, Nairobi, Kenya
5. 5Africa Health Research Institute, Durban, South Africa
6. 6South African Population Research Infrastructure Network, Department of Science and Innovation and South African Medical Research Council, Durban, South Africa