A Pragmatic Randomized Trial to Evaluate the Effectiveness of High-Dose Quadrivalent Influenza Vaccine vs. Standard-Dose Quadrivalent Influenza Vaccine in Older Adults

Last updated: May 14, 2025
Sponsor: Tor Biering-Sørensen
Overall Status: Active - Not Recruiting

Phase

4

Condition

Influenza

Treatment

Standard-Dose Quadrivalent Influenza Vaccine

High-Dose Quadrivalent Influenza Vaccine

Clinical Study ID

NCT05517174
DANFLU-2
2022-500657-17-00
  • Ages > 65
  • All Genders
  • Accepts Healthy Volunteers

Study Summary

The purpose of this pragmatic randomized trial is to evaluate the relative vaccine effectiveness of high-dose quadrivalent influenza vaccine (QIV-HD) vs. standard-dose quadrivalent influenza vaccine (QIV-SD) in older adults. Participants will be randomized 1:1 to either QIV-HD or QIV-SD.

Eligibility Criteria

Inclusion

Inclusion Criteria:

  • Age 65 years and above (this inclusion criterion will be modified according to theDanish government's official recommendations for the 2022/2023 and 2023/2024influenza seasons)

  • Informed consent form has been signed and dated

Exclusion

Exclusion Criteria:

  • There are no specific exclusion criteria for this study

Study Design

Total Participants: 339700
Treatment Group(s): 2
Primary Treatment: Standard-Dose Quadrivalent Influenza Vaccine
Phase: 4
Study Start date:
September 22, 2022
Estimated Completion Date:
August 31, 2025

Study Description

The study is a pragmatic, registry-based, open-label, active-controlled, individually randomized trial. The Danish nationwide administrative health registries will be used for data collection including baseline information, follow-up data, and safety monitoring. The study aims to randomize 339,700 participants over 3 influenza seasons. In each season, participants will be individually randomized 1:1 to receive either QIV-HD or QIV-SD. During the 2023/2024 and 2024/2025 seasons, up to 12,000 participants will be enrolled in a sub-cohort where participants are asked to perform home self-swabs and answer symptom questionnaires in case of influenza-like illness to enable further assessment of the impact of QIV-HD vs. QIV-SD on patient-reported outcomes among individuals with influenza-like illness and laboratory-confirmed influenza.

Connect with a study center

  • Center for Translational Cardiology and Pragmatic Randomized Trials, Department of Cardiology, Copenhagen University Hospital - Herlev and Gentofte

    Hellerup, Hovedstaden 2900
    Denmark

    Site Not Available

  • Danske Lægers Vaccinations Service

    Søborg, 2860
    Denmark

    Site Not Available

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