Assessment of the comprehensiveness of paediatric national immunisation programmes in Europe: expert validation and future perspectives

Background: The breadth of protection of National Immunisation Programmes (NIPs) across Europe varies, however, this has not been assessed within published literature. Therefore, a framework was developed to assess the comprehensiveness of pediatric NIPs in Europe. This study aimed to validate and further develop criteria used to cluster countries into three tiers. Research design and methods: Independent Europe-based experts (n = 23) in the field of pediatric vaccination were invited to participate in a double-blinded modified Delphi panel, with two online survey rounds and a virtual consensus meeting. Consensus was defined as ≥ 80% of experts rating their agreement/disagreement on a 9-point Likert scale. Results: The number of preventable diseases covered by an NIP, simplification of the vaccination calendar, strengthened protection by increasing serotype, degree of funding and epidemiological factors were considered key concepts for consideration of the comprehensiveness of pediatric NIPs in Europe. Experts highlighted that the framework should be extended to include adolescent vaccines and populations up to 18 years of age. Consensus regarding further amendments to the framework was also reached. Conclusions: This Delphi panel validated a framework to assess the comprehensiveness of European NIPs. The framework can be used to facilitate discussions to help countries improve and expand the breadth of protection provided by their NIP.