Affiliation: | 1Social and Mathematical Epidemiology Group, London School of Hygiene and Tropical Medicine, Faculty of Public Health and Policy, 15–17 Tavistock Place, London WC1H 9SH, UK;2Department of Mathematics, University College London, Gower Street, London WC1E 6BT, UK;3MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK |