InfluenzaPhase 4FLUNITY-HDNCT06506812
Pooled Analysis of Methodologically Harmonized Pragmatic Randomized Trials of High-Dose vs. Standard-Dose Influenza Vaccine Against Severe Clinical Outcomes
A Phase 4 study testing High-Dose Influenza Vaccine and Standard-Dose Influenza Vaccine in people with Influenza, run by Tor Biering-Sørensen at 1 site in Denmark.
Trial summary
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… Read more about this study
- Who is it for?
- Ages 65 years and older
- Conditions the study is for
- Influenza
- What is being tested?
- High-Dose Influenza Vaccine and Standard-Dose Influenza Vaccine
- Type of treatment
- Vaccines, Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 466,320 participants
- Where
- 1 siteDenmark
- Study dates
- 31 May 2025to 31 Aug 2025
- Phase
- Phase 4
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 65 years and older
- All sexes
- No healthy volunteers
- Older adult
Who may be able to join
- 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
Who cannot join
- Low data quality
- Influenza circulation threshold was not met in any of the study seasons
- Severe under-enrollment in all seasons
Trial locations and contacts
1 site in 1 country.
Denmark1 site
Center for Translational Cardiology and Pragmatic Randomized Trials, Department of Cardiology, Copenhagen University Hospital - Herlev and Gentofte
Hellerup, Capital Region, 2900
About this study
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.
- Conditions
- Influenza
- Being tested
- High-Dose Influenza Vaccine, Standard-Dose Influenza Vaccine
- Keywords
- Influenza, Vaccination, Pragmatic, Registry, Pneumonia, Respiratory, Cardiovascular, Meta-analysis
- Medical subject headings
- Influenza, Human, Pneumonia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
High-Dose Influenza VaccineBiological
For this arm, the high-dose quadrivalent influenza vaccine Efluelda®/Fluzone® High-Dose Quadrivalent will be used.
Standard-Dose Influenza VaccineBiological
Any standard-dose quadrivalent influenza vaccine administered in the governmental influenza vaccine programs may be used.
| Study group | Role | What they receive |
|---|---|---|
| High-Dose Influenza Vaccine | Experimental | Single injection of high-dose influenza vaccine at Day 0 Receives: Biological: High-Dose Influenza Vaccine |
| Standard-Dose Influenza Vaccine | Active comparator | Single injection of standard-dose influenza vaccine at Day 0 Receives: Biological: Standard-Dose Influenza Vaccine |
What is being measured
The primary outcome is the main question the study is designed to answer.
Hospitalization for influenza or pneumonia
Measured: ≥14 days after vaccination up to 8 months
Secondary outcomes (6)
Hospitalization for any cardio-respiratory disease
Measured: ≥14 days after vaccination up to 8 months
Laboratory-confirmed influenza hospitalization
Measured: ≥14 days after vaccination up to 8 months
All-cause hospitalization
Measured: ≥14 days after vaccination up to 8 months
All-cause mortality
Measured: ≥14 days after vaccination up to 8 months
Hospitalization for influenza
Measured: ≥14 days after vaccination up to 8 months
Hospitalization for pneumonia
Measured: ≥14 days after vaccination up to 8 months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted18 Jul 2024
- Study start31 May 2025
- Primary completion31 May 2025
- Study completion31 Aug 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (2)Papers the sponsor has linked to this study.
- Other trials for InfluenzaStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 4
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 466,320 participants (actual)
Sponsor and investigators
- Lead sponsor
- Tor Biering-Sørensen
- Sponsor type
- University, hospital or other
- Collaborators
- Sanofi, Hospital Clinico Universitario de Santiago
- Responsible party
- Sponsor-investigator, Tor Biering-Sørensen, Herlev and Gentofte Hospital
- Investigators
- Tor Biering-Sørensen, MD, MSc, MPH, PhD, Study chair, Center for Translational Cardiology and Pragmatic Randomized Trials, Department of Cardiology, Copenhagen University Hospital - Herlev and Gentofte
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06506812
- Sponsor's protocol ID
- DANFLU/GALFLU pooled analysis
- Acronym
- FLUNITY-HD
- Status last verified
- Sep 2025
- First submitted
- 12 Jul 2024
- Last updated
- 12 Sep 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: In each trial, baseline and endpoint data will be collected from administrative health registries, which are subject to local legislation and can only be made available to a third party under certain conditions. Please contact the sponsor in case of any inquiries.
Publications
Johansen ND, Modin D, Pardo-Seco J, Rodriguez-Tenreiro-Sanchez C, Loiacono MM, Harris RC, Dufournet M, van Aalst R, Chit A, Larsen CS, Larsen L, Wiese L, Dalager-Pedersen M, Claggett BL, Janstrup KH, Duran-Parrondo C, Pineiro-Sotelo M, Cribeiro-Gonzalez M, Conde-Pajaro M, Miras-Carballal S, Gonzalez-Perez JM, Solomon SD, Sivapalan P, Martel CJ, Jensen JUS, Martinon-Torres F, Biering-Sorensen T; DANFLU-2 Study Group and the GALFLU Trial Team. High-Dose Versus Standard-Dose Influenza Vaccine and Cardiovascular Outcomes in Older Adults: The FLUNITY-HD Prespecified Pooled Analysis. Circulation. 2026 Mar 17;153(11):798-806. doi: 10.1161/CIRCULATIONAHA.125.077801. Epub 2025 Nov 10.
PubMed 41212981Johansen ND, Modin D, Pardo-Seco J, Rodriguez-Tenreiro-Sanchez C, Loiacono MM, Harris RC, Dufournet M, van Aalst R, Chit A, Larsen CS, Larsen L, Wiese L, Dalager-Pedersen M, Claggett BL, Janstrup KH, Duran-Parrondo C, Pineiro-Sotelo M, Cribeiro-Gonzalez M, Conde-Pajaro M, Miras-Carballal S, Gonzalez-Perez JM, Solomon SD, Sivapalan P, Martel CJ, Jensen JUS, Martinon-Torres F, Biering-Sorensen T; DANFLU-2 Study Group; GALFLU Trial Team. Effectiveness of high-dose influenza vaccine against hospitalisations in older adults (FLUNITY-HD): an individual-level pooled analysis. Lancet. 2025 Nov 22;406(10518):2425-2434. doi: 10.1016/S0140-6736(25)01742-8. Epub 2025 Oct 17.
PubMed 41115437
Study at a glance
From the registry record, last updated by the sponsor on 12 Sep 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Pooled Analysis of Methodologically Harmonized Pragmatic Randomized Trials of High-Dose vs. Standard-Dose Influenza Vaccine Against Severe Clinical Outcomes
- ClinicalTrials.gov ID
- NCT06506812
- Acronym / sponsor ID
- FLUNITY-HD / DANFLU/GALFLU pooled analysis
- Conditions
- Influenza
- Keywords
- Influenza, Vaccination, Pragmatic, Registry, Pneumonia, Respiratory, Cardiovascular, Meta-analysis
- Phase
- Phase 4
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 466,320 participants (actual)
- Lead sponsor
- Tor Biering-SørensenUniversity, hospital or other
- Collaborators
- Sanofi, Hospital Clinico Universitario de Santiago
- Study start
- 31 May 2025 (actual)
- Primary completion
- 31 May 2025 (actual)
- Study completion
- 31 Aug 2025 (actual)
- First posted
- 18 Jul 2024 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| High-Dose Influenza Vaccine | Experimental | Biological: High-Dose Influenza VaccineSingle injection of high-dose influenza vaccine at Day 0 |
| Standard-Dose Influenza Vaccine | Active comparator | Biological: Standard-Dose Influenza VaccineSingle injection of standard-dose influenza vaccine at Day 0 |
Who may qualify
- Ages
- 65 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Older adult
Key inclusion criteria (1 listed)
- 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
Key exclusion criteria (3 listed)
- Low data quality
- Influenza circulation threshold was not met in any of the study seasons
- Severe under-enrollment in all seasons
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| High-Dose Influenza VaccineFor this arm, the high-dose quadrivalent influenza vaccine Efluelda®/Fluzone® High-Dose Quadrivalent will be used. | Biological | High-Dose Influenza Vaccine |
| Standard-Dose Influenza VaccineAny standard-dose quadrivalent influenza vaccine administered in the governmental influenza vaccine programs may be used. | Biological | Standard-Dose Influenza Vaccine |
Primary outcome
Hospitalization for influenza or pneumonia
Time frame: ≥14 days after vaccination up to 8 months
6 secondary outcomes
Hospitalization for any cardio-respiratory disease
Time frame: ≥14 days after vaccination up to 8 months
Laboratory-confirmed influenza hospitalization
Time frame: ≥14 days after vaccination up to 8 months
All-cause hospitalization
Time frame: ≥14 days after vaccination up to 8 months
All-cause mortality
Time frame: ≥14 days after vaccination up to 8 months
Hospitalization for influenza
Time frame: ≥14 days after vaccination up to 8 months
Hospitalization for pneumonia
Time frame: ≥14 days after vaccination up to 8 months
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 12 Sep 2025.
- Derived from this study: PubMed 41212981Johansen ND, Modin D, Pardo-Seco J, Rodriguez-Tenreiro-Sanchez C, Loiacono MM, Harris RC, Dufournet M, van Aalst R, Chit A, Larsen CS, Larsen L, Wiese L, Dalager-Pedersen M, Claggett BL, Janstrup KH, Duran-Parrondo C, Pineiro-Sotelo M, Cribeiro-Gonzalez M, Conde-Pajaro M, Miras-Carballal S, Gonzalez-Perez JM, Solomon SD, Sivapalan P, Martel CJ, Jensen JUS, Martinon-Torres F, Biering-Sorensen T; DANFLU-2 Study Group and the GALFLU Trial Team. High-Dose Versus Standard-Dose Influenza Vaccine and Cardiovascular Outcomes in Older Adults: The FLUNITY-HD Prespecified Pooled Analysis. Circulation. 2026 Mar 17;153(11):798-806. doi: 10.1161/CIRCULATIONAHA.125.077801. Epub 2025 Nov 10.
- Derived from this study: PubMed 41115437Johansen ND, Modin D, Pardo-Seco J, Rodriguez-Tenreiro-Sanchez C, Loiacono MM, Harris RC, Dufournet M, van Aalst R, Chit A, Larsen CS, Larsen L, Wiese L, Dalager-Pedersen M, Claggett BL, Janstrup KH, Duran-Parrondo C, Pineiro-Sotelo M, Cribeiro-Gonzalez M, Conde-Pajaro M, Miras-Carballal S, Gonzalez-Perez JM, Solomon SD, Sivapalan P, Martel CJ, Jensen JUS, Martinon-Torres F, Biering-Sorensen T; DANFLU-2 Study Group; GALFLU Trial Team. Effectiveness of high-dose influenza vaccine against hospitalisations in older adults (FLUNITY-HD): an individual-level pooled analysis. Lancet. 2025 Nov 22;406(10518):2425-2434. doi: 10.1016/S0140-6736(25)01742-8. Epub 2025 Oct 17.
- Individual participant dataSharing planned: Yes. In each trial, baseline and endpoint data will be collected from administrative health registries, which are subject to local legislation and can only be made available to a third party under certain conditions. Please contact the sponsor in case of any inquiries.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Tor Biering-Sørensen, MD, MSc, MPH, PhD study chair
Center for Translational Cardiology and Pragmatic Randomized Trials, Department of Cardiology, Copenhagen University Hospital - Herlev and Gentofte
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 4 study testing High-Dose Influenza Vaccine and Standard-Dose Influenza Vaccine in people with Influenza, run by Tor Biering-Sørensen at 1 site in Denmark.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 3 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 12 Sep 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Denmark. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 4 studies take place after a treatment is approved, to learn more about its long-term benefits and risks in everyday use.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Hospitalization for influenza or pneumonia (time frame: ≥14 days after vaccination up to 8 months). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT06506812, which also lists 2 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 12 Sep 2025.