Objective:

To assess the effectiveness of the 2025–2026 seasonal influenza vaccine in reducing outpatient visits and hospitalizations due to influenza during the specified season.

Approach:

Key Findings:

• Vaccine reduced outpatient visits by 22% to 34% and hospitalizations by 30% among adults, while pediatric patients showed the strongest protection with 38% to 41% effectiveness.
• Vaccine effectiveness against influenza A(H3N2) was 35% for outpatient visits and 38% for hospitalizations in adults.
• Influenza B showed higher outpatient effectiveness estimates of 71% and 45% in different networks.

Interpretation:

Despite antigenic drift in circulating viruses, the vaccine effectively reduced influenza-related morbidity, particularly in pediatric populations, highlighting the need for continued vaccination efforts.

Limitations:

• Preliminary results may change as the season progresses.
• Unmeasured confounding factors were not modeled, which may affect results.
• Potential misclassification of vaccination status could impact effectiveness estimates.
• Limited sample sizes in certain strata affected estimates.

Conclusion:

Vaccination significantly reduced the risk of influenza-associated outpatient visits and hospitalizations, underscoring the importance of influenza vaccination for all eligible individuals, especially in light of antigenic drift.

Sources:

• CDC Morbidity and Mortality Weekly Report
Attribution Notice

This content is an AI-generated, fully rewritten summary based on a published scholarly article. It does not reproduce the original text and is not a substitute for the original publication. Readers are encouraged to consult the source for full context, data, and methodology.