1 Kirby Institute, University of New South Wales, Level 6, Wallace Wurth Building, High Street, UNSW Sydney, Kensington, NSW 2052, Australia.
2 Department of Global Health and Development, Faculty of Public Health and Policy, London School of Hygiene and Tropical Medicine, 15-17 Tavistock Place, London WC1H 9SH, UK.
3 Institute for Global Health, University College London, 30 Guilford Street, London WC1N 1EH, UK.
4 Faculty of Infectious and Tropical Disease, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK.
5 Department of Family Medicine and Primary Care, School of Clinical Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.