Catch-Up Vaccination Intervention and Study of Infant Vaccine Hesitancy in Health District in Palermo (Italy).

Abstract

Background: Despite the introduction in 2017 of mandatory vaccination for the hexavalent and the measles-mumps-rubella-varicella vaccines, childhood vaccination coverage in Sicily (Italy) remains below the recommended and safety threshold of 95%. A catch-up vaccination intervention was implemented for the pediatric population of the 2022-2023 birth cohorts residing in a health district of Palermo (Bagheria) where in 2024, 24-month coverage for polio and measles was 77.29% and 77.62%, respectively.

Methods: A cross-sectional study with a before-after component was conducted between June 2025 and December 2025, with the aim of evaluating the increase in vaccination coverage. A questionnaire was administered to the parents of non-compliant children to investigate the determinants of infant vaccine hesitancy.

Results: Collaboration with primary care pediatricians and the organization of active call sessions and extra vaccination sessions resulted in an increase in vaccination coverage of approximately 10-12 percentage points in both birth cohorts. The investigation of the determinants of vaccination adherence showed some significant associations: "perception of infectious disease risk" (OR: 7.91; p = 0.009) and "expectations of a positive outcome from vaccination" (OR: 8.62; p = 0.003). Vaccine information sources such as the internet and media were associated with refusal of catch-up vaccination (OR: 0.47, p < 0.001; and OR: 0.13, p = 0.026, respectively).

Conclusions: Despite methodological limitations, such as the self-reported nature of the survey data, the study demonstrated the usefulness of local strategies aimed at vaccination catch-up, representing a valuable example of local public health practice and effectively contributing to improved vaccination coverage in the pediatric population.