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

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.