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EUROPE – Early estimates published in Eurosurveillance indicate that the influenza vaccine for the 2024/2025 season offers moderate protection against influenza A virus strains and strong protection against influenza B. This interim assessment, based on data from multiple European studies, provides valuable insights for upcoming vaccine composition decisions and public health strategies.
The analysis included data from eight studies conducted in Denmark, the United Kingdom (UK), and through the European Union’s Vaccine Effectiveness, Burden, and Impact Studies (VEBIS) networks, encompassing several European countries. The studies employed a test-negative design, examining vaccine effectiveness in both primary care and hospital settings.
The dominant virus strain in Europe during the 2024/2025 season was influenza A(H1N1)pdm09, with influenza A(H3N2) and influenza B/Victoria lineage also circulating.1
Overall, the influenza vaccine demonstrated moderate effectiveness in primary care, ranging from 40% to 53%. However, protection was lower among adults aged 65 and over, with no protection observed in EU studies and 38% effectiveness in the UK study. In hospital settings, vaccine effectiveness ranged from 34% to 52% across all ages.
Specifically, against influenza A(H1N1)pdm09, vaccine effectiveness in primary care ranged from 30% to 72%, while in hospital settings, it ranged from 46% to 53%. Protection against influenza A(H3N2) varied significantly by age, with effectiveness ranging from 29% to 47% in primary care and 31% to 49% in hospital settings.
Notably, the vaccine exhibited strong protection against influenza B, with effectiveness estimates ranging from 58% to 74% in primary care and 73% to 88% in hospital settings.
The study highlights the importance of continued influenza vaccination, particularly among target groups, despite variations in effectiveness among virus subtypes and age groups. Given the lower protection observed against certain influenza A strains and among older adults, the authors recommend strengthening other preventive measures.
“Influenza vaccination prevented from one-third to more than three-quarters of influenza infections in primary care or hospital settings among the vaccinated,” the researchers stated. “However, given the lower vaccine effectiveness for specific virus subtypes and among older adults in certain studies, other prevention measures should also be strengthened.”
The study authors also noted that end-of-season studies with larger sample sizes and additional information on virus characteristics will provide further clarity on the variations in effectiveness.
The study, titled “Interim 2024/25 influenza vaccine effectiveness: eight European studies, September 2024 to January 2025,” was authored by Angela MC Rose et al. and published in Eurosurveillance (2025).2 DOI: 10.2807/1560-7917.ES.2025.30.7.2500102.
Disclaimer: This article is based on interim influenza vaccine effectiveness estimates published in Eurosurveillance. Vaccine effectiveness can vary based on several factors, including circulating virus strains, individual health conditions, and age.3 These findings should not be interpreted as definitive medical advice. Consult with a healthcare professional for personalized recommendations regarding influenza vaccination and prevention.
