Marta Bertran a, Snehal M Pinto Pereira b, Manjula D Nugawela c, Terence Stephenson c, Roz Shafran c, Tamsin Ford d, Marta Buszewicz e, Elizabeth Whittaker f, Isobel Heyman c, Terry Y Segal g, Emma Dalrymple c, Shamez N Ladhani a, i, ⁎ 
a Immunisations and Vaccine Preventable Diseases Division, UK Health Security Agency, 61 Colindale Avenue, London NW9 5EQ, United Kingdom
b Division of Surgery & Interventional Science, Faculty of Medical Sciences, University College London, WC1E 6BT, United Kingdom
c UCL Great Ormond Street Institute of Child Health, 30 Guilford Street, London, WC1N 1EH, United Kingdom
d Department of Psychiatry, University of Cambridge, Hershel Smith Building Cambridge Biomedical Campus, CB2 0SZ, United Kingdom
e Research Department of Primary Care & Population Health, University College London Medical School London United Kingdom
f Department of Paediatric Infectious Diseases, Imperial College Healthcare NHS Trust, London, United Kingdom
g Paediatric and Adolescent Division, University College London Hospitals NHS Foundation Trust, London, United Kingdom
i Paediatric Infectious Diseases Research Group, St. George's University of London, Cranmer Terrace, London, SW17 0RE, United Kingdom