Pooled Analysis of Methodologically Harmonized Pragmatic Randomized Trials of High-Dose vs. Standard-Dose Influenza Vaccine Against Severe Clinical Outcomes

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

COMPLETED

Clinical Phase

PHASE4

Total Enrollment

466320 participants

Study Classification

INTERVENTIONAL

Study Start Date

2025-05-31

Study Completion Date

2025-08-31

Brief Summary

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This prespecified analysis will pool the datasets from two pragmatic randomized trials evaluating the relative vaccine effectiveness of high-dose vs. standard-dose influenza vaccine against severe clinical outcomes: the DANFLU-2 (A Pragmatic Randomized Trial to Evaluate the Effectiveness of High-Dose Quadrivalent Influenza Vaccine vs. Standard-Dose Quadrivalent Influenza Vaccine in Older Adults) trial and the GALFLU (Pragmatic Randomized Trial to Evaluate the Effectiveness of High-Dose Quadrivalent Influenza Vaccine vs. Standard-Dose Quadrivalent Influenza Vaccine in Adults Aged 65 to 79 Years in Galicia, Spain) trial. The purpose of the pooled analysis is to ensure adequate statistical power for evaluating relative vaccine effectiveness against severe clinical outcomes and to increase generalizability of the results by combining data from two countries.

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Detailed Description

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Conditions

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Influenza

Study Design

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Allocation Method

RANDOMIZED

Intervention Model

PARALLEL

Primary Study Purpose

TREATMENT

Blinding Strategy

NONE

Study Groups

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High-Dose Influenza Vaccine

Single injection of high-dose influenza vaccine at Day 0

Group Type EXPERIMENTAL

High-Dose Influenza Vaccine

Intervention Type BIOLOGICAL

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

Standard-Dose Influenza Vaccine

Single injection of standard-dose influenza vaccine at Day 0

Group Type ACTIVE_COMPARATOR

Standard-Dose Influenza Vaccine

Intervention Type BIOLOGICAL

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

Interventions

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High-Dose Influenza Vaccine

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

Intervention Type BIOLOGICAL

Standard-Dose Influenza Vaccine

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

Intervention Type BIOLOGICAL

Eligibility Criteria

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Inclusion Criteria

* Pragmatic trials conducted to estimate the relative vaccine effectiveness of high-dose influenza vaccine compared with standard-dose influenza vaccine using the DANFLU-2 protocol or a protocol developed based on the DANFLU-2 protocol