National Institutes of Health, NIH, (K23AI159518); Bill and Melinda Gates Foundation, BMGF, (OPP1209135); Wellcome Trust, WT, (215091/Z/18/Z); UK Research and Innovation, UKRI, (COVLT0022); Medical Research Council, MRC, (MR/P020372/1); National Institute for Health and Care Research, NIHR; Department of Health and Social Care, DH; Foreign, Commonwealth and Development Office, FCDO