DARWIN EU® – Proof-of-concept: Preparedness for annual seasonal influenza vaccine effectiveness studies - Vaccine coverage and incidence of influenza-related outcomes

Study type

• Study topic:
  Disease /health condition

  Human medicinal product
• Study type:
  Non-interventional study
• Scope of the study:
  Disease epidemiology

  Validation of study variables (exposure outcome covariate)
• Data collection methods:
  Secondary use of data

Non-interventional study

• Non-interventional study design:
  Cohort

Study drug and medical condition

• Medicinal product name:
  INFLUENZA VACCINE
• Anatomical Therapeutic Chemical (ATC) code:
  (J07BB) Influenza vaccines

  Influenza vaccines

Population studied

• Short description of the study population:
  Objective 1: Population-level drug utilisation on influenza vaccine ; Inclusion criteria; • All individuals present in each influenza season (1st October-30th April) during the study period of 01/10/2015 to 30/04/2024 (or the latest available date); Exclusion criteria; • Individuals with missing information on sex and age ; ; Objective 2: Patient-level characterisation on use and type of influenza vaccine; Inclusion criteria; • All individuals receiving influenza vaccine in each influenza season during the period of 01/10/2015 to 30/04/2024 (or the latest available date); Exclusion criteria; • Individuals with missing information on sex and age ; Objective 3: Patient-level characterisation of influenza vaccine recipients; Inclusion criteria; • All individuals receiving influenza vaccine in each influenza season during the period of 01/10/2015 to 30/04/2024 (or the latest available date); • Minimum 365 days of available history before index date; Exclusion criteria; • Individuals with missing information in sex and age ; ; Objective 4: Population-level descriptive epidemiology of influenza-related outcomes ; Inclusion criteria; • All individuals with at least one of the defined influenza-related outcomes in each influenza season during the period of 01/10/2015 to 30/04/2024 (or the latest available date); Exclusion criteria; • Individuals with missing information in sex and age;

Study design details

• Study design:
  A cohort study will be conducted using routinely collected health data from six databases from six countries across Europe and in five EU member states
• Main study objective:
  1. To estimate the period prevalence of influenza vaccination in the general population for each influenza season from 2015/16 to 2023/24, overall and stratified by age group and sex. ; 2. To characterise influenza vaccine use within each influenza season by month of vaccination, vaccine brand, and route of administration, stratified by age group and sex. ; 3. To describe the baseline demographic characteristics, comorbidities, immunocompromised status, and receipt of other vaccinations of individuals receiving any influenza vaccine in each influenza season. ; 4. To describe the background incidence rates of influenza-related clinical outcomes, hospitalisations, and deaths in the general population, and crude incidence rates of influenza-related clinical outcomes, hospitalisations, and deaths in the vaccinated and unvaccinated populations, overall and stratified by age group and sex in each influenza season.
• Data analysis plan:
  Period prevalence of influenza vaccines will be estimated in the general population for each influenza season from October to April, overall and stratified by age group and sex. The statistical analyses will be performed based on OMOP CDM mapped data using IncidencePrevalence R package. A minimum cell counts of 5 will be used when reporting results, with any smaller count reported as “<5”.