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Influenza Vaccine Effectiveness in UK Healthcare Workers Surpasses Expectations

Strategic Insights

— 1 min read

Research conducted by the UK Health Security Agency has revealed a 39.9% vaccine effectiveness against influenza infection among healthcare workers in the UK during the winter of 2023-24. This study, part of the SIREN cohort, has significant implications for public health and workforce protection. The findings emphasize the importance of seasonal influenza vaccination in reducing infections among healthcare workers, thereby protecting patients and reducing workforce pressures.

Key Takeaways:

  • The SIREN cohort study, conducted from September 2023 to March 2024, included 4934 hospital-based healthcare workers, with a median age of 55 years and a majority being female (78.7%) and white (85.6%).
  • Influenza vaccination was received by 78.2% of participants, with 5.4% testing positive for influenza, of which 85.3% reported acute respiratory infection symptoms.
  • Adjusted vaccine effectiveness was 39.9%, with similar results obtained using case-control (41.2%) and test-negative case-control (45.9%) approaches.
  • The vaccine effectiveness estimate of 40% is consistent with previous estimates for symptomatic patients.
  • The study calculated that seasonal influenza vaccination could potentially prevent over 50,000 infections among the combined UK healthcare workforce.

Statistics:

  • 4934 healthcare workers participated in the SIREN cohort study (median age 55 years).
  • 78.2% of participants received influenza vaccination.
  • 5.4% of participants tested positive for influenza (266 out of 4934).
  • 85.3% of participants with positive influenza tests reported acute respiratory infection symptoms.
  • Adjusted vaccine effectiveness was 39.9% (95% CI 21.8-53.8).
  • Case-control analysis showed vaccine effectiveness of 41.2%.
  • Test-negative case-control analysis showed vaccine effectiveness of 45.9%.
  • Estimated 50,000 infections prevented among UK healthcare workforce.

Sources:

  • NewsRx. Findings from UK Health Security Agency Provides New Data about Vaccination (Effectiveness of influenza vaccination against infection in UK healthcare workers during winter 2023-24: The SIREN cohort study). Medical Letter on the CDC & FDA. September 14, 2025; p 429.
  • Effectiveness of influenza vaccination against infection in UK healthcare workers during winter 2023-24: The SIREN cohort study. Journal of Infection, 2025;91(3):106585.

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