Clinical Scorecard: Effectiveness of influenza vaccination in preventing hospitalization among children aged 6–72 months: a test-negative study in Southern Italy, 2022–2026

At a Glance

Key Highlights

• The analysis included 935 children: 207 influenza-positive cases and 728 influenza-negative controls.
• Receipt of at least one influenza vaccine dose was associated with adjusted vaccine effectiveness of 62.5% (95% CI 34.4%–78.5%) against influenza-associated hospitalization.
• Adjusted effectiveness was 80.3% (95% CI 43.8%–93.1%) for at least one LAIV dose and 50.9% (95% CI 6.9%–74.2%) for at least one IIV dose.
• Subtype-specific effectiveness against A(H1N1)pdm09 was 82.3% (95% CI 25.2%–95.8%) for at least one dose; the A(H3N2) estimate was 43.5% (95% CI −11.0%–71.3%) and was not statistically significant.
• Influenza B vaccine effectiveness could not be estimated because no vaccinated influenza B cases were observed.

Guideline-Based Recommendations

Diagnosis

• The study enrolled children hospitalized for acute respiratory infection who underwent influenza testing; influenza-positive children were cases and influenza-negative children were controls.

Management

• The article reports Italian Ministry of Health recommendations for IIV from 6 months of age and LAIV from 2 years of age; both are provided free of charge to children aged 6–72 months.

Monitoring & Follow-up

• The authors describe seasonal and setting-specific vaccine-effectiveness estimates as necessary because effectiveness may vary with circulating subtypes, vaccine formulation, antigenic concordance, prior vaccination or infection, and host characteristics.

Risks

• Children younger than 5 years are described as having high frequencies of influenza infection, medically attended illness, and hospitalization; influenza can cause serious complications, including pneumonia.

Patient & Prescribing Data

Children aged 6–72 months hospitalized for acute respiratory infection in the Foggia district during the 2022–2023 through 2025–2026 influenza seasons.

At least one vaccine dose was associated with adjusted effectiveness of 62.5% against influenza-associated hospitalization; full vaccination was associated with 61.9% effectiveness. Estimates were 80.3% for at least one LAIV dose and 50.9% for at least one IIV dose.

Clinical Best Practices

• The study assessed influenza vaccine effectiveness against hospitalization over four seasons in children aged 6–72 months in the Foggia district.
• The article reports Italian recommendations for IIV from 6 months of age and LAIV from 2 years of age; both are provided free of charge to children aged 6–72 months.

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