Interim 2019/20 influenza vaccine effectiveness: six European studies, September 2019 to January 2020

Euro Surveill. 2020 Mar;25(10):2000153. doi: 10.2807/1560-7917.ES.2020.25.10.2000153.

Abstract

BackgroundInfluenza A(H1N1)pdm09, A(H3N2) and B viruses were co-circulating in Europe between September 2019 and January 2020.AimTo provide interim 2019/20 influenza vaccine effectiveness (VE) estimates from six European studies, covering 10 countries and both primary care and hospital settings.MethodsAll studies used the test-negative design, although there were some differences in other study characteristics, e.g. patient selection, data sources, case definitions and included age groups. Overall and influenza (sub)type-specific VE was estimated for each study using logistic regression adjusted for potential confounders.ResultsThere were 31,537 patients recruited across the six studies, of which 5,300 (17%) were cases with 5,310 infections. Most of these (4,466; 84%) were influenza A. The VE point estimates for all ages were 29% to 61% against any influenza in the primary care setting and 35% to 60% in hospitalised older adults (aged 65 years and over). The VE point estimates against A(H1N1)pdm09 (all ages, both settings) was 48% to 75%, and against A(H3N2) ranged from -58% to 57% (primary care) and -16% to 60% (hospital). Against influenza B, VE for all ages was 62% to 83% (primary care only).ConclusionsInfluenza vaccination is of continued benefit during the ongoing 2019/20 influenza season. Robust end-of-season VE estimates and genetic virus characterisation results may help understand the variability in influenza (sub)type-specific results across studies.

Keywords: Europe; influenza; multicentre study; test-negative design; vaccine effectiveness.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Aged
  • Case-Control Studies
  • Child
  • Child, Preschool
  • Europe / epidemiology
  • Female
  • Humans
  • Immunization
  • 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 / prevention & control
  • Male
  • Middle Aged
  • Outcome Assessment, Health Care
  • Population Surveillance*
  • Seasons
  • Sensitivity and Specificity
  • Vaccination / statistics & numerical data*
  • Young Adult

Substances

  • Influenza Vaccines