Effectiveness of Influenza Vaccination in Children Aged 6-59 Months during the Inaugural 2022-2023 Season in Andalusia, Spain

J Pediatr. 2025 Jul:282:114558. doi: 10.1016/j.jpeds.2025.114558. Epub 2025 Mar 21.

Abstract

Objective: To estimate the effectiveness of influenza vaccination when systematic vaccination against influenza was introduced for the first time in Andalusia for the children aged 6 through 59 months, an age group with one of the highest incidence and influenza-related hospitalization rates each season.

Study design: Population-based, retrospective cohort study during the 2022-2023 influenza season of 287 661 children aged 6-59 months at the beginning of the inaugural 2022-2023 vaccination campaign. Adjusted vaccine effectiveness (VE) was calculated by estimating multivariable logistic regression models for likelihood of influenza diagnosis in vaccinated and unvaccinated children.

Results: In children aged 6-59 months, VE was 51% (95% CI: 48%-53%) for preventing infection and 69% (95% CI: 56%-79%) for preventing influenza-related hospitalization. In children aged 6-23 months, VE was 53% (95% CI: 48%-57%) for preventing influenza and 76% (95% CI: 57%-87%) for preventing hospitalization due to influenza. In both subpopulations, VE was significantly higher with the two-dose vaccination schedule.

Conclusions: Influenza vaccination shows moderate effectiveness in preventing influenza and high effectiveness in preventing influenza-related hospitalization in children aged 6-59 months. This highlights the importance of strengthening influenza vaccination coverage in this age group.

Keywords: children; effectiveness; hospitalization; influenza; severity; vaccination.

MeSH terms

  • Child, Preschool
  • Female
  • Hospitalization / statistics & numerical data
  • Humans
  • Infant
  • Influenza Vaccines* / administration & dosage
  • Influenza, Human* / epidemiology
  • Influenza, Human* / prevention & control
  • Male
  • Retrospective Studies
  • Seasons
  • Spain / epidemiology
  • Vaccination* / statistics & numerical data
  • Vaccine Efficacy*

Substances

  • Influenza Vaccines