1. Medical Research Council Unit, The Gambia at the London School of Hygiene & Tropical Medicine , Banjul , The Gambia
2. Department of Pediatrics, Center for Vaccine Development and Global Health, University of Maryland School of Medicine , Baltimore, Maryland , USA
3. Center for Vaccine Development and Global Health, University of Maryland School of Medicine , Baltimore, Maryland , USA
4. Centre pour le Développement des Vaccins du Mali (CVD-Mali) , Bamako , Mali
5. Center for Global Health Research, Kenya Medical Research Institute , Kisumu , Kenya
6. Department of Medicine, University of Maryland School of Medicine , Baltimore, Maryland , USA
7. Division of Global Health Protection, US Centers for Disease Control and Prevention , Nairobi , Kenya
8. Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia , Charlottesville, Virginia , USA
9. School of Public Health, Qingdao University , Qingdao , China
10. Department of Epidemiology and Public Health, University of Maryland School of Medicine , Baltimore, Maryland , USA