KEMRI-Wellcome Trust Research Programme, P.O Box 43640 - 00100, Nairobi, Kenya. jaluvaala@kemri-wellcome.org. Department of Paediatrics and Child Health, College of Health Sciences, University of Nairobi, Kenyatta National Hospital, P. O. Box 19676-00202, Nairobi, Kenya. jaluvaala@kemri-wellcome.org. Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ, UK. jaluvaala@kemri-wellcome.org. Centre for Statistics in Medicine, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Botnar Research Centre, University of Oxford, Oxford, OX3 7LD, UK. KEMRI-Wellcome Trust Research Programme, P.O Box 43640 - 00100, Nairobi, Kenya. Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ, UK. The Childhood Acute Illness & Nutrition (CHAIN) Network, P.O Box 43640 - 00100, Nairobi, Kenya.