Influenza vaccine effectiveness against hospitalization in children aged 6–72 months: a test-negative study in the Southern Italy, 2022–2026 - Report - MDSpire
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Effectiveness of influenza vaccination in preventing hospitalization among children aged 6–72 months: a test-negative study in Southern Italy, 2022–2026
Clinical Report: Influenza Vaccination and Pediatric Hospitalization in Southern Italy
Overview
This hospital-based test-negative study assessed influenza vaccine effectiveness against influenza-associated hospitalization among children aged 6–72 months in Foggia, Italy, across four seasons from 2022–2023 through 2025–2026. Of 935 children hospitalized with acute respiratory infection and tested for influenza, 207 were influenza-positive and 728 were influenza-negative; the supplied results do not include vaccine-effectiveness estimates.
Background
Children younger than 5 years experience frequent influenza infection, medically attended illness, and hospitalization, and influenza can cause serious complications including pneumonia. Italian surveillance has reported the highest incidence among children aged 0–4 years, while vaccination coverage among eligible children remains below target levels. Italy recommends inactivated influenza vaccine from 6 months of age and live attenuated influenza vaccine from 2 years of age, with both provided free to children aged 6–72 months. Because vaccine performance can vary by season and setting, the study evaluated effectiveness against hospitalization over four successive seasons in southern Italy.
Data Highlights
Measure
Finding
Study period and setting
Four influenza seasons, 2022–2023 through 2025–2026; Foggia district, southern Italy
Children hospitalized with acute respiratory infection and tested
955
Final study cohort
935 children after excluding 20 with unknown vaccination status
Influenza-positive cases
207
Influenza-negative controls
728
Median age
31 months among cases; 27 months among controls (p = 0.0126)
Co-infections
57.5% of cases versus 35.0% of controls (p < 0.0001)
ICU admission
2.4% of cases versus 0.5% of controls (p = 0.0153)
Most frequently detected influenza subtype
A(H3N2): 93/207 cases (44.9%)
Key Findings
The final cohort included 935 hospitalized children aged 6 months–6 years: 207 influenza-positive cases and 728 influenza-negative controls.
Cases were older than controls by median age: 31 months versus 27 months (p = 0.0126).
Co-infections were more frequent among influenza-positive cases than controls (57.5% versus 35.0%; p < 0.0001).
ICU admission was uncommon but occurred more often among cases than controls (2.4% versus 0.5%; p = 0.0153).
A(H3N2) was the most frequently reported subtype, accounting for 93 of 207 influenza-positive cases (44.9%).
The supplied study results describe the cohort and clinical characteristics but do not provide vaccine-effectiveness estimates; related articles listed in the source context address other populations, outcomes, or settings.
Clinical Implications
The study addresses influenza-associated hospitalization in a population for whom Italian guidance recommends vaccination from 6 months of age, but the supplied results do not report vaccine-effectiveness estimates. The source context reports that Italian vaccination is offered free to children aged 6–72 months and that coverage in Apulia remained below target levels.
Conclusion
This four-season study characterized influenza-positive and influenza-negative hospitalized children in Foggia, including subtype distribution and differences in co-infection and ICU admission. The provided material is insufficient to state the study’s estimate of vaccine effectiveness against hospitalization.
