1 Department of Science and Innovation, South African Population Research Infrastructure Network (SAPRIN), South African Medical Research Council, South Africa.
2 MRC/Wits Rural Public Health and Health Transitions Research Unit, School of Public Health, University of the Witwatersrand, Johannesburg, South Africa.
3 DIMAMO Population Health Research Centre, University of Limpopo, Turfloop, South Africa.
4 Africa Health Research Institute, Mtubatuba, South Africa.