CI

At a glance

ClinicalIndex Comparison Record
Phase 4Completed· 332,438 enrolled
Drug / intervention
High-Dose Quadrivalent Influenza Vaccine +1 morebiological
Likely dose
Not stated in record
Structured eligibility isn't available for this trial yet — see the full criteria in the Eligibility tab below.

Standardized by ClinicalIndex from the ClinicalTrials.gov record · verify against the source.

Search/NCT05517174
NCT05517174Phase 4Completed
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A Pragmatic Randomized Trial to Evaluate the Effectiveness of High-Dose Quadrivalent Influenza Vaccine vs. Standard-Dose Quadrivalent Influenza Vaccine in Older Adults

Tor Biering-Sørensen·interventional·Posted Aug 26, 2022·Updated Sep 12, 2025

In Brief

A Phase 4 clinical trial evaluating High-Dose Quadrivalent Influenza Vaccine and Standard-Dose Quadrivalent Influenza Vaccine for Influenza. Completed, enrolled 332,438 participants across 2 sites.

Detailed 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.

Study Details

Study Typeinterventional
Allocation--
Masking--
Primary Purpose--
ConditionsInfluenza
CountriesDenmark
CollaboratorsSanofi, Statens Serum Institut

Timeline

Phase 4CompletedFinished
2023202420252026
First PostedAug 26, 2022
Enrollment StartSep 22, 2022
Primary CompletionMay 31, 2025
Study CompletionAug 31, 2025
TodayJul 2, 2026
Enrollment to primary: 2.7 yearsPosted 3.9 years ago

Interventions

High-Dose Quadrivalent Influenza Vaccinebiological

For this arm, the high-dose quadrivalent influenza vaccine Efluelda®/Fluzone® High-Dose Quadrivalent will be used.

Standard-Dose Quadrivalent Influenza Vaccinebiological

Any standard-dose quadrivalent influenza vaccine administered in the Danish governmental influenza vaccine program may be used.