Early vaccine effectiveness estimates against medically attended laboratory-confirmed influenza based on influenza surveillance, Beijing, China, 2024/25 season

Euro Surveill. 2025 Feb;30(7):2500084. doi: 10.2807/1560-7917.ES.2025.30.7.2500084.

Abstract

We estimated early influenza vaccine effectiveness (VE) for the 2024/25 season in outpatients, in Beijing using a test-negative design. A(H1N1)pdm09 dominated (99.3%), all sequenced strains (n = 38) clustered in clade 6B.1A.5a.2a, and 37 of 38 antigenically similar to the vaccine strain. VE against any influenza virus infection was 48.5% (95% CI: 34.8-59.5) and 48.7% (95% CI: 35.1-59.7) against A(H1N1)pdm09. Vaccination in the current or previous season against any influenza showed a VE of 52.5% to 54.9%, compared to no vaccination in both seasons.

Keywords: A(H1N1)pdm09; early epidemic; influenza; vaccine effectiveness.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Beijing / epidemiology
  • Child
  • Child, Preschool
  • China / epidemiology
  • Female
  • Humans
  • Infant
  • Influenza A Virus, H1N1 Subtype* / genetics
  • Influenza A Virus, H1N1 Subtype* / immunology
  • Influenza A Virus, H1N1 Subtype* / isolation & purification
  • Influenza A Virus, H3N2 Subtype / genetics
  • Influenza A Virus, H3N2 Subtype / immunology
  • Influenza A Virus, H3N2 Subtype / isolation & purification
  • Influenza Vaccines* / administration & dosage
  • Influenza Vaccines* / immunology
  • Influenza, Human* / diagnosis
  • Influenza, Human* / epidemiology
  • Influenza, Human* / prevention & control
  • Influenza, Human* / virology
  • Male
  • Middle Aged
  • Population Surveillance
  • Seasons
  • Vaccination / statistics & numerical data
  • Vaccine Efficacy*
  • Young Adult

Substances

  • Influenza Vaccines