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January 18, 2026Eurosurveillance11 citationsOpen Access

Interim vaccine effectiveness against influenza virus among outpatients, France, October 2025 to January 2026

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ACAllan De ClercqUniversité de LilleFBFrançois BlanquartCentre National de la Recherche ScientifiqueVVVincent VieillefondHoneywell (France)

Key Points

  • This analysis aimed to estimate the early effectiveness of the influenza vaccine among outpatients in France during the 2025/26 season.
  • Analyzed vaccine effectiveness in outpatients with influenza virus positivity
  • Included 18,816 individuals, with 5,451 testing positive for influenza
  • Categorized effectiveness by age groups: ≥ 65 years, 18–64 years, and 0–17 years
  • Vaccine effectiveness was 28% for individuals aged ≥ 65 years
  • Demonstrated a 45% effectiveness for those aged 18–64 years
  • Showed a 57% effectiveness for the age group of 0–17 years

Abstract

In Europe, the 2025/26 seasonal influenza epidemic started in October 2025. Co-circulation of A(H3N2) and A(H1N1)pdm09 was observed in several countries including France. We estimated early vaccine effectiveness (VE) against influenza virus in French outpatients (5,451 positives/18,816 negatives). A significant VE across all age groups was measured: 28% (95% CI: 17–37) for those aged ≥ 65 years, 45% (95% CI: 36–53) for 18–64-year-olds and 57% (95% CIs: 29–74) for 0–17-year-olds. Reinforcing vaccination uptake is warranted.

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Cite This Study

Clercq et al. (2026) studied this question.

synapsesocial.com/papers/696c79cde45ebfc9113cd58chttps://doi.org/10.2807/1560-7917.es.2026.31.2.2500992
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