1. International Centre for Evidence in Disability, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK
2. Maternal, Adolescent, Reproductive and Child Health Centre, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK
3. MRC/UVRI & LSHTM Uganda Research Unit, Entebbe, Uganda
4. Institute of Translational Medicine, University of Liverpool, Liverpool, L69 7TX, UK