1. Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
2. Head of School Nursing and Specialist Nursing Services, Bristol and South Gloucestershire, UK
3. Population Health Sciences, Bristol Medical School, University of Bristol; National Institute for Health Research Applied Research Collaboration West, University Hospitals Bristol and Weston NHS Foundation Trust, Bristol, UK
4. Screening and Immunisation Manager, Public Health England; NHS England and NHS Improvement South West, UK
5. Lead Consultant for Screening and Immunisation, Public Health England/NHS England and NHS Improvement South West, UK
6. Consultant Paediatrician, Department of Paediatric Immunology and Infectious Diseases, Bristol Children's Hospital, Bristol, UK