1. Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
2. Disease Dynamics Unit, Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
3. Paediatric Infectious Diseases Research Group & Vaccine Institute, St George’s, University of London, and St George’s University Hospitals NHS Trust, London, United Kingdom
4. Unit of Health-Care Epidemiology, Big Data Institute, Nuffield Department of Population Health, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom