Influenza Vaccination in Children During the First Two Seasons of Routine Vaccination Programs (2023-24 and 2024-25) in Central Catalonia, Spain: A Retrospective Study.

Vaccination is the primary method of preventing influenza. During the 2023-24 season, the influenza vaccination for all children between 6 and 59 months was introduced for the first time in Spain. To assess the coverage and adherence of influenza vaccination in childhood during the first two seasons of a vaccination program, as well as to identify the factors associated with influenza vaccination in all children under 5 years of age and those from 5 to 14 years of age with risk factors. Retrospective observational study. All children eligible for the flu vaccine in Central Catalonia during the 2023-24 and 2024-25 seasons were included. A total of 39,937 children were studied. Of these, 79.1% had not been vaccinated for influenza in either of the seasons studied. Influenza vaccination coverage in childhood was 18.1% and 19.3% in the 2023-24 and 2024-25 seasons, respectively. In the 6- to 59-month age range, coverage was 19.1% and 28.9% in the 2023-24 and 2024-25 seasons, respectively. The adherence to vaccination in both seasons was 17%. Some variables (being a non-native person, living in an urban area, having more than one risk factor, or certain underlying conditions) were associated with the influenza vaccination. Coverage and adherence to influenza vaccination in childhood are very low, despite the implementation of a routine influenza vaccination program.