1 The Centre for Mathematical Modelling of Infectious Diseases, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK; School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan. Electronic address: akira.endo@lshtm.ac.uk.
2 Carolina Population Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
3 Centre for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), Bilthoven, Netherlands; Center for Marine Environmental Studies, Ehime University, Matsuyama, Japan.