1. Oxford Centre for Global Health Research, Nuffield Department of Medicine, University of Oxford, Oxford, UK
2. KEMRI-Wellcome Trust Research Programme, Nairobi, Kenya
3. MARCH Centre, London School of Hygiene and Tropical Medicine, London, UK
4. Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK
5. Department of Economics, Verona University, Verona, Italy
6. KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya