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| Name | Class |
|---|---|
| Sanofi | INDUSTRY |
| Hospital Clinico Universitario de Santiago | OTHER |
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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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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| High-Dose Influenza Vaccine | Experimental | Single injection of high-dose influenza vaccine at Day 0 |
|
| Standard-Dose Influenza Vaccine | Active Comparator | Single injection of standard-dose influenza vaccine at Day 0 |
|
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| High-Dose Influenza Vaccine | Biological | For this arm, the high-dose quadrivalent influenza vaccine Efluelda®/Fluzone® High-Dose Quadrivalent will be used. |
|
| Measure | Description | Time Frame |
|---|---|---|
| Hospitalization for influenza or pneumonia | ≥14 days after vaccination up to 8 months |
| Measure | Description | Time Frame |
|---|---|---|
| Hospitalization for any cardio-respiratory disease | ≥14 days after vaccination up to 8 months | |
| Laboratory-confirmed influenza hospitalization | ≥14 days after vaccination up to 8 months | |
| Measure | Description | Time Frame |
|---|---|---|
| Hospitalization for influenza or pneumonia (alternate definition) | ≥14 days after vaccination up to 8 months | |
| Hospitalization for pneumonia (alternate definition) | ≥14 days after vaccination up to 8 months |
Inclusion Criteria:
Exclusion Criteria:
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| Name | Affiliation | Role |
|---|---|---|
| Tor Biering-Sørensen, MD, MSc, MPH, PhD | Center for Translational Cardiology and Pragmatic Randomized Trials, Department of Cardiology, Copenhagen University Hospital - Herlev and Gentofte | Study Chair |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Center for Translational Cardiology and Pragmatic Randomized Trials, Department of Cardiology, Copenhagen University Hospital - Herlev and Gentofte | Hellerup | Capital Region | 2900 | Denmark |
| PubMed Identifier | Type | Citation | Retractions |
|---|---|---|---|
| 41212981 | Derived | 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. | |
| 41115437 |
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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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| Standard-Dose Influenza Vaccine | Biological | Any standard-dose quadrivalent influenza vaccine administered in the governmental influenza vaccine programs may be used. |
|
| All-cause hospitalization |
| ≥14 days after vaccination up to 8 months |
| All-cause mortality | ≥14 days after vaccination up to 8 months |
| Hospitalization for influenza | ≥14 days after vaccination up to 8 months |
| Hospitalization for pneumonia | ≥14 days after vaccination up to 8 months |
| Hospitalization for influenza (alternate definition) | ≥14 days after vaccination up to 8 months |
| Hospitalization for any respiratory disease | ≥14 days after vaccination up to 8 months |
| Hospitalization for any cardiovascular disease | ≥14 days after vaccination up to 8 months |
| Hospitalization for myocardial infarction | ≥14 days after vaccination up to 8 months |
| Hospitalization for heart failure | ≥14 days after vaccination up to 8 months |
| Hospitalization for atrial fibrillation | ≥14 days after vaccination up to 8 months |
| Hospitalization for stroke | ≥14 days after vaccination up to 8 months |
| Major adverse cardiovascular events (MACE) defined as a composite of hospitalization for acute myocardial infarction, hospitalization for stroke, and cardiovascular death | ≥14 days after vaccination up to 8 months |
| MACE defined as a composite of hospitalization for acute myocardial infarction, hospitalization for stroke, hospitalization for heart failure, and cardiovascular death (alternate definition #1) | ≥14 days after vaccination up to 8 months |
| MACE defined as a composite of hospitalization for acute myocardial infarction, hospitalization for stroke, and all-cause death (alternate definition #2) | ≥14 days after vaccination up to 8 months |
| Hospitalization requiring mechanical ventilation | ≥14 days after vaccination up to 8 months |
| Laboratory-confirmed influenza | ≥14 days after vaccination up to 8 months |
| Laboratory-confirmed pneumococcal pneumonia | ≥14 days after vaccination up to 8 months |
| Laboratory-confirmed COVID-19 | ≥14 days after vaccination up to 8 months |
| Cardio-respiratory mortality | ≥14 days after vaccination up to 8 months |
| Respiratory mortality | ≥14 days after vaccination up to 8 months |
| Cardiovascular mortality | ≥14 days after vaccination up to 8 months |
| In-hospital mortality | ≥14 days after vaccination up to 8 months |
| Intensive care unit admission | ≥14 days after vaccination up to 8 months |
| Any hospital contact associated with laboratory-confirmed influenza | ≥14 days after vaccination up to 8 months |
| Any exacerbation of pre-existing chronic obstructive pulmonary disease | ≥14 days after vaccination up to 8 months |
| Any exacerbation of pre-existing chronic obstructive pulmonary disease (alternate definition) | ≥14 days after vaccination up to 8 months |
| Severe exacerbation of pre-existing chronic obstructive pulmonary disease | ≥14 days after vaccination up to 8 months |
| Severe exacerbation of pre-existing chronic obstructive pulmonary disease (alternate definition) | ≥14 days after vaccination up to 8 months |
| Any exacerbation of pre-existing asthma | ≥14 days after vaccination up to 8 months |
| Any exacerbation of pre-existing asthma (alternate definition) | ≥14 days after vaccination up to 8 months |
| Severe exacerbation of pre-existing asthma | ≥14 days after vaccination up to 8 months |
| Severe exacerbation of pre-existing asthma (alternate definition) | ≥14 days after vaccination up to 8 months |
| Exacerbation of pre-existing heart failure | ≥14 days after vaccination up to 8 months |
| Exacerbation of pre-existing heart failure (alternate definition) | ≥14 days after vaccination up to 8 months |
| Hospitalization for pericarditis | ≥14 days after vaccination up to 8 months |
| Hospitalization for myocarditis | ≥14 days after vaccination up to 8 months |
| New-onset dementia | ≥14 days after vaccination up to 8 months |
| Derived |
| 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; 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. |
| ID | Term |
|---|---|
| D007251 | Influenza, Human |
| D011014 | Pneumonia |
| ID | Term |
|---|---|
| D012141 | Respiratory Tract Infections |
| D007239 | Infections |
| D009976 | Orthomyxoviridae Infections |
| D012327 | RNA Virus Infections |
| D014777 | Virus Diseases |
| D012140 | Respiratory Tract Diseases |
| D008171 | Lung Diseases |
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| ID | Term |
|---|---|
| D007252 | Influenza Vaccines |
| ID | Term |
|---|---|
| D014765 | Viral Vaccines |
| D014612 | Vaccines |
| D001688 | Biological Products |
| D045424 | Complex Mixtures |
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