1. 1Department of Immunisation, Hepatitis and Blood Safety, Public Health England, London, UK
2. 2Public Health, Epidemiology and Biostatistics, Ambition Health Private Limited, Gurgaon, India
3. 3National Technical Advisory Group on Immunization Secretariat, National Institute of Health and Family Welfare, New Delhi, India
4. 4North East PHE Centre, Public Health England, Newcastle upon Tyne, UK
5. 5Health Protection Team, Public Health England, East of England, Harlow, UK
6. 6Department of Statistics Modelling and Economics, Public Health England, London, UK