Effectiveness of influenza vaccines in children aged 6 to 59 months: a test-negative case-control study at primary care and hospital level, Spain 2023/24

Euro Surveill. 2024 Oct;29(40):2400618. doi: 10.2807/1560-7917.ES.2024.29.40.2400618.

Abstract

During 2023/24, all children aged 6 to 59 months were targeted for seasonal influenza vaccination in Spain nationally. Using a test-negative case-control design with sentinel surveillance data, we estimated adjusted influenza vaccine effectiveness (IVE) against any influenza type to be 70% (95% confidence interval (CI): 51 to 81%) for primary care patients with acute respiratory illness (ARI) and 77% (95% CI: 21 to 93%) for hospitalised patients with severe ARI. In primary care, where most subtyped viruses (61%; 145/237) were A(H1N1), adjusted IVE was 77% (95% CI: 56 to 88%) against A(H1N1)pdm09.

Keywords: children; influenza; test-negative design; vaccine effectiveness.

MeSH terms

  • Case-Control Studies
  • Child, Preschool
  • Female
  • Hospitalization / statistics & numerical data
  • Hospitals
  • Humans
  • Infant
  • Influenza A Virus, H1N1 Subtype* / immunology
  • Influenza A Virus, H1N1 Subtype* / isolation & purification
  • Influenza A Virus, H3N2 Subtype / immunology
  • Influenza A Virus, H3N2 Subtype / isolation & purification
  • Influenza B virus / immunology
  • Influenza B virus / isolation & purification
  • Influenza Vaccines* / administration & dosage
  • Influenza Vaccines* / immunology
  • Influenza, Human* / epidemiology
  • Influenza, Human* / prevention & control
  • Male
  • Primary Health Care*
  • Seasons
  • Sentinel Surveillance*
  • Spain / epidemiology
  • Vaccination* / statistics & numerical data
  • Vaccine Efficacy

Substances

  • Influenza Vaccines