1. Vaccines and Immunity Theme, Medical Research Council (MRC) Unit–The Gambia, Banjul, The Gambia; Department of Epidemiology and Biostatistics, McGill University, Montreal, Quebec, Canada
2. Vaccines and Immunity Theme, Medical Research Council (MRC) Unit–The Gambia, Banjul, The Gambia
3. Center for International Health, Division of Infectious Diseases and Tropical Medicine, Medical Center of the University of Munich, German Center for Infection Research, Munich Partner Site, Munich, Germany
4. Centre for International Health, Department of Preventive and Social Medicine, University of Otago, Dunedin, New Zealand
5. Vaccines and Immunity Theme, Medical Research Council (MRC) Unit–The Gambia, Banjul, The Gambia; Centre for International Child Health, Academic Department of Paediatrics, St Mary's Campus, Imperial College London, London, UK