London Metropolitan University - Department of Computing, Communications Technology & Mathematics (CCTM), Public Health England - Immunisation, Hepatitis, and Blood Safety Department, Government of the United Kingdom, Department of Health and Social Care, Public Health England, Respiratory Department, Government of the United Kingdom - Respiratory and Vaccine Preventable Bacterial Reference Unit, Government of the United Kingdom - Respiratory and Vaccine Preventable Bacterial Reference Unit, Public Health England - Immunisation and Countermeasures Division and Public Health England - Statistics, Modelling, and Economics Department