doi: 10.1371/journal.pone.0288612. Affiliations Affiliations 1 Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, United Kingdom. 2 Immunisation and Vaccine Preventable Diseases Division and Public Health Programmes, UK Health Security Agency, London, United Kingdom. 3 Influenza and Respiratory Virology & Polio Reference Service, UK Health Security Agency, London, United Kingdom. 4 NIHR Health Protection Research Unit, Imperial College London, London, United Kingdom.