1. Department of Non-Communicable Disease Epidemiology, London School of Hygiene and Tropical Medicine , Keppel Street, London WC1E 7HT , UK
2. Institute of Health Informatics, University College London , 222 Euston Road, London NW1 2DA , UK
3. Department of Medical Statistics, London School of Hygiene and Tropical Medicine , Keppel Street, London WC1E 7HT , UK
4. Institute of Epidemiology and Health Care, University College London , 1-19 Torrington Place, London NW1 2DA , UK
5. National Institute for Health Research Health Protection Research Unit in Immunisation, London School of Hygiene and Tropical Medicine in partnership with the UK Health Security Agency , Keppel Street, London WC1E 7HT , UK
6. Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine , Keppel Street, London WC1E 7HT , UK
7. Population Health Sciences, Bristol Medical School, University of Bristol , Queens Road, Bristol BS8 1QU , UK