1 Migrant Health Research Group, St George's, University of London, London SW17 0QT, UK. Electronic address: s.hargreaves@sgul.ac.uk.
2 Migrant Health Research Group, St George's, University of London, London SW17 0QT, UK; Faculty of Public Health and Policy, London School of Hygiene & Tropical Medicine, London, UK.
3 European Centre for Disease Prevention and Control, Solna, Sweden.
4 Faculty of Public Health and Policy, London School of Hygiene & Tropical Medicine, London, UK.
5 Norwegian Institute of Public Health, Oslo, Norway.