University of the Witwatersrand - Medical Research Council: Respiratory and Meningeal Pathogens Research Unit, University of the Witwatersrand - Vaccines and Infectious Diseases Analytics Research Unit, University of the Witwatersrand - South African Medical Research Council, University of the Witwatersrand - South African Medical Research Council, University of the Witwatersrand - South African Medical Research Council, University of the Witwatersrand - Department of Internal Medicine, University of the Witwatersrand - South African Medical Research Council Vaccines and Infectious Diseases Analytical Research Unit, University of the Witwatersrand - South African Medical Research Council, University of the Witwatersrand - South African Medical Research Council, University of the Witwatersrand - Department of Obstetrics & Gynaecology, University of the Witwatersrand - Department of Intensive Care, University of the Witwatersrand - School of Clinical Medicine, University of the Witwatersrand - Department of Internal Medicine, University of Oxford - Centre for Tropical Medicine & Global Health, University of the Witwatersrand - Vaccines and Infectious Diseases Analytics Research Unit and Independent