Feasibility of Conducting a Study Comparing High-Dose Influenza Vaccines to Standard-Dose Influenza Vaccines in Danish Citizens Aged 65-79 Years

Feasibility of Randomizing Danish Citizens Aged 65-79 Years to High-Dose Quadrivalent Influenza Vaccine vs. Standard-Dose Quadrivalent Influenza Vaccine in a Pragmatic Registry-Based Setting

Status

Active, not recruiting

Phases

Phase 2

Study type

Interventional

Source

EU CTR

Registry ID

EUCTR2021-003170-31-DK

Enrollment

40000

Registered

2021-06-10

Start date

2021-08-16

Completion date

Unknown

Last updated

2022-03-02

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Prevention of influenza infection in adults aged 65-79 years MedDRA version: 20.0 Level: PT Classification code 10022000 Term: Influenza System Organ Class: 10021881 - Infections and infestations

Interventions

Trade Name: Efluelda® Product Name: High-Dose Quadrivalent Influenza Vaccine Pharmaceutical Form: Suspension for injection in pre-filled syringe INN or Proposed INN: INFLUENZA VACCINE (SPLIT VIRION, I

Eligibility

Sex/Gender

All

Inclusion criteria

Inclusion criteria: 1. Persons aged 65-79 years are eligible for inclusion into this trial 2. Informed consent form has been signed and dated Are the trial subjects under 18? no Number of subjects for this age range: F.1.2 Adults (18-64 years) no F.1.2.1 Number of subjects for this age range F.1.3 Elderly (>=65 years) yes F.1.3.1 Number of subjects for this age range 40000

Exclusion criteria

Exclusion criteria: 1. Allergy/hypersensitivity towards the influenza vaccines used in this study 2. The presence of any contraindication towards vaccination at the day of vaccination

Design outcomes

Primary

Measure	Time frame
Main Objective: Descriptive objective 1: Identifying and recruiting a large sample of Danish citizens aged 65-79 years in the coming 2021/2022 influenza season to assess feasibility, reliability, and validity of the proposed pragmatic RCT study design as assessed by operational endpoints;Secondary Objective: Descriptive objective 2: Demonstrating comparability of the QIV-HD vs QIV-SD cohorts to the overall Danish population aged 65-79 years and the population recruited as candidate participants for this study Descriptive objective 3: Assuming influenza circulates in Denmark during the 2021/22 season, validate the feasibility conditions by describing event rates in the QIV-HD and QIV-SD participants and calculating relative vaccine effectiveness (rVE) for: -Hospitalization for influenza and/or pneumonia -Hospitalization for respiratory disease -Hospitalization for cardio-respiratory disease Descriptive objective 4: Regardless of influenza circulation, validate the feasibility conditions by describing event rates in the QIV-HD and QIV-SD participants and calculating rVE for: -Hospitalization for cardiovascular disease -Hospitalization for any cause -All-cause mortality Descriptive objective 5: Calculate rVE for: -Hospitalization for COVID-19;Primary end point(s): Descriptive objective 1: The following descriptive end-points/indicators will used to assess the feasibility of identifying, recruiting and randomizing a large sample of Danish citizens aged 65-79 years to QIV-HD vs QIV-SD: -Number of persons contacted by recruitment letter -Number of participants included and randomized to QIV-HD or QIV-SD. -Agreement between randomization assignment to QIV-HD or QIV-SD and actual received vaccine -Balance between groups in terms of number of subjects in each arm and baseline characteristics;Timepoint(s) of evaluation of this end point: May 31, 2022	—

Measure

Time frame

Main Objective: Descriptive objective 1: Identifying and recruiting a large sample of Danish citizens aged 65-79 years in the coming 2021/2022 influenza season to assess feasibility, reliability, and validity of the proposed pragmatic RCT study design as assessed by operational endpoints;Secondary Objective: Descriptive objective 2: Demonstrating comparability of the QIV-HD vs QIV-SD cohorts to the overall Danish population aged 65-79 years and the population recruited as candidate participants for this study Descriptive objective 3: Assuming influenza circulates in Denmark during the 2021/22 season, validate the feasibility conditions by describing event rates in the QIV-HD and QIV-SD participants and calculating relative vaccine effectiveness (rVE) for: -Hospitalization for influenza and/or pneumonia -Hospitalization for respiratory disease -Hospitalization for cardio-respiratory disease Descriptive objective 4: Regardless of influenza circulation, validate the feasibility conditions by describing event rates in the QIV-HD and QIV-SD participants and calculating rVE for: -Hospitalization for cardiovascular disease -Hospitalization for any cause -All-cause mortality Descriptive objective 5: Calculate rVE for: -Hospitalization for COVID-19;Primary end point(s): Descriptive objective 1: The following descriptive end-points/indicators will used to assess the feasibility of identifying, recruiting and randomizing a large sample of Danish citizens aged 65-79 years to QIV-HD vs QIV-SD: -Number of persons contacted by recruitment letter -Number of participants included and randomized to QIV-HD or QIV-SD. -Agreement between randomization assignment to QIV-HD or QIV-SD and actual received vaccine -Balance between groups in terms of number of subjects in each arm and baseline characteristics;Timepoint(s) of evaluation of this end point: May 31, 2022

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Secondary

Measure	Time frame
Secondary end point(s): Descriptive objective 2: The following descriptive end-points/indicators will used to demonstrate comparability between the study populations and overall Danish general population aged 65-79 years and to the population recruited as candidate participants: -Comparison of baseline characteristics for the QIV-HD and QIV-SD groups to the overall Danish general population aged 65-79 years -Comparison of baseline characteristics for the QIV-HD and QIV-SD groups to the 65-79 years age group population in the DLVS database used for recruitment Descriptive objective 3: Adequate influenza circulation for the 2021/2022 season will be prespecified prior to study start. Given that influenza circulation is adequate, the feasibility conditions will be evaluated by describing event rates in the QIV-HD and QIV-SD participants and calculating relative vaccine effectiveness (rVE) for: -Hospitalization for influenza and/or pneumonia -Hospitalization for respiratory disease -Hospitalization for cardio-respiratory disease Descriptive objective 4: Regardless of influenza circulation, the feasibility conditions will be evaluated by describing event rates in the QIV-HD and QIV-SD participants and calculating rVE for: -Hospitalization for cardiovascular disease -Hospitalization from any cause -All-cause mortality Descriptive objective 5: Calculate rVE for: -Hospitalization for COVID-19;Timepoint(s) of evaluation of this end point: May 31, 2022	—

Measure

Time frame

Secondary end point(s): Descriptive objective 2: The following descriptive end-points/indicators will used to demonstrate comparability between the study populations and overall Danish general population aged 65-79 years and to the population recruited as candidate participants: -Comparison of baseline characteristics for the QIV-HD and QIV-SD groups to the overall Danish general population aged 65-79 years -Comparison of baseline characteristics for the QIV-HD and QIV-SD groups to the 65-79 years age group population in the DLVS database used for recruitment Descriptive objective 3: Adequate influenza circulation for the 2021/2022 season will be prespecified prior to study start. Given that influenza circulation is adequate, the feasibility conditions will be evaluated by describing event rates in the QIV-HD and QIV-SD participants and calculating relative vaccine effectiveness (rVE) for: -Hospitalization for influenza and/or pneumonia -Hospitalization for respiratory disease -Hospitalization for cardio-respiratory disease Descriptive objective 4: Regardless of influenza circulation, the feasibility conditions will be evaluated by describing event rates in the QIV-HD and QIV-SD participants and calculating rVE for: -Hospitalization for cardiovascular disease -Hospitalization from any cause -All-cause mortality Descriptive objective 5: Calculate rVE for: -Hospitalization for COVID-19;Timepoint(s) of evaluation of this end point: May 31, 2022

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Countries

Denmark

Contacts

Public ContactNiklas Dyrby Johansen

Cardiovascular Non-Invasive Imaging Research Laboratory, Department of Cardiology, Herlev and Gentofte Hospital

niklas.dyrby.johansen@regionh.dk+4520204794

Outcome results

None listed

Source: EU CTR (via WHO ICTRP) · Data processed: Feb 4, 2026