1. Faculty of Infectious and Tropical disease, London School of Hygiene and Tropical Medicine , London , United Kingdom
2. International Health, Health Systems Center, John Hopkins University , Baltimore , USA
3. Viral Immunology Research Group, Malawi-Liverpool-Wellcome Trust Clinical Research Programme , Blantyre , Malawi
4. South African Medical Research Council Vaccines and Infectious Diseases Analytics Research Unit, Faculty of Health Sciences, University of the Witwatersrand , Johannesburg , South Africa