1. Public Health Research, Kenya Medical Research Institute–Wellcome Trust Research Programme , Nairobi , Kenya
2. Epidemiology and Demography, Kenya Medical Research Institute–Wellcome Trust Research Programme , Kilifi , Kenya
3. Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford , Oxford , United Kingdom
4. Epidemiology and Population Health, London School of Hygiene & Tropical Medicine , London , United Kingdom
5. College of Health and Medical Sciences, Haramaya University , Harar , Ethiopia
6. Warwick Medical School, University of Warwick , Coventry , United Kingdom
7. Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, University of Oxford , Oxford , United Kingdom