University of Oxford, University of Oxford - Nuffield Department of Primary Care Health Sciences, University College London - Institute for Global Health, University of Oxford - Nuffield Department of Primary Care Health Sciences, University of Oxford - Nuffield Department of Primary Care Health Sciences, Public Health England - Immunisation and Countermeasures Division, Public Health England Colindale, University of Oxford - Nuffield Department of Primary Care Health Sciences, UK Health Security Agency - COVID-19 National Epidemiology Cell, UK Health Security Agency, Government of the United Kingdom - Public Health England, University of Oxford - Nuffield Department of Primary Care Health Sciences, Public Health England Colindale, University of Oxford - Nuffield Department of Primary Care Health Sciences, Public Health England - Immunisation, Hepatitis, and Blood Safety Department, University of Oxford - Nuffield Department of Primary Care Health Sciences, University of Oxford - Nuffield Department of Primary Care Health Sciences, Royal College of General Practitioners - Royal College of General Practitioners (RCGP) Research and Surveillance Centre (RSC), Public Health England - Virus Reference Department, University of Oxford - Nuffield Department of Primary Care Health Sciences, University of Oxford - Nuffield Department of Primary Care Health Sciences and University of Oxford - Nuffield Department of Primary Care Health Sciences

University of Oxford - Nuffield Department of Primary Care Health Sciences, University of Oxford - Nuffield Department of Primary Care Health Sciences, University of Oxford - Nuffield Department of Primary Care Health Sciences, affiliation not provided to SSRN, affiliation not provided to SSRN, University of Oxford - Nuffield Department of Primary Care Health Sciences, affiliation not provided to SSRN, Royal College of General Practitioners, University of Oxford - Nuffield Department of Primary Care Health Sciences, Swansea University - Population Data Science, Queen’s University Belfast - Public Health Agency, Swansea University - Population Data Science, Swansea University - Population Data Science, Swansea University - Department of Education and Childhood Studies, University of Strathclyde - Department of Mathematics & Statistics, BREATHE – The Health Data Research Hub for Respiratory Health, Royal College of General Practitioners - Royal College of General Practitioners (RCGP) Research and Surveillance Centre (RSC), University of Edinburgh - Usher Institute, University of Oxford - Nuffield Department of Primary Care Health Sciences and University of Oxford

University of Oxford - Nuffield Department of Primary Care Health Sciences, University of Oxford - Nuffield Department of Primary Care Health Sciences, University of Oxford - Nuffield Department of Primary Care Health Sciences, Nuffield Department of Primary Care Health Sciences, University of Oxford, University of Oxford - Nuffield Department of Primary Care Health Sciences, Public Health England - Immunisation and Countermeasures Division, University of Oxford - Nuffield Department of Primary Care Health Sciences, UK Health Security Agency - COVID-19 National Epidemiology Cell, University of Oxford - Nuffield Department of Primary Care Health Sciences, Government of the United Kingdom - Public Health England, University of Oxford - Nuffield Department of Primary Care Health Sciences, University of Oxford - Nuffield Department of Primary Care Health Sciences, Public Health England Colindale, Royal College of General Practitioners, University of Oxford, University of Oxford - Nuffield Department of Primary Care Health Sciences, University of Oxford, Public Health England - Immunisation, Hepatitis, and Blood Safety Department, Nuffield Department of Primary Care Health Sciences, University of Oxford, Government of the United Kingdom - Public Health England, Public Health England - Virus Reference Department, Royal College of General Practitioners - Royal College of General Practitioners (RCGP) Research and Surveillance Centre (RSC), University of Oxford - Nuffield Department of Primary Care Health Sciences and University of Oxford