A Pragmatic Randomized Trial to Evaluate the Effectiveness of High-Dose Quadrivalent Influenza Vaccine vs. Standard-Dose Quadrivalent Influenza Vaccine in Older Adults

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.

Timeline

Start

2022-09-22

Primary completion

2025-05-31

Completion

2025-08-31

Publications

• Nielsen AB, Johansen ND, Modin D, Loiacono MM, Harris RC, Dufournet M, Larsen CS, Larsen L, Wiese L, Dalager-Pedersen M, Claggett BL, Janstrup KH, Bartholdy KV, Bernholm KF, Borchsenius JIH, Davidovski FS, Davodian LW, Dons M, Duus LS, Espersen C, Fussing FH, Jensen AMR, Landler NE, Langhoff ACF, Lassen MCH, Ottosen CI, Sengelov M, Skaarup KG, Pareek M, Muller-Wieland D, Solomon SD, Landray MJ, Gislason GH, Kober L, Sivapalan P, Martel CJ, Jensen JUS, Biering-Sorensen T. High-Dose vs Standard-Dose Influenza Vaccine in Older Adults With Diabetes: A Secondary Analysis of the DANFLU-2 Randomized Clinical Trial. JAMA Intern Med. 2026 Mar 1;186(3):311-320. doi: 10.1001/jamainternmed.2025.7286.
• Johansen ND, Modin D, Loiacono MM, Harris RC, Dufournet M, Larsen CS, Larsen L, Wiese L, Dalager-Pedersen M, Claggett BL, Janstrup KH, Bartholdy KV, Bernholm KF, Borchsenius JIH, Davidovski FS, Davodian LW, Dons M, Duus LS, Espersen C, Fussing FH, Jensen AMR, Landler NE, Langhoff ACF, Lassen MCH, Nielsen AB, Ottosen CI, Sengelov M, Skaarup KG, Solomon SD, Landray MJ, Gislason GH, Kober L, Ralfkiaer L, Nealon J, Sivapalan P, Martel CJ, Jensen JUS, Biering-Sorensen T. High-Dose Influenza Vaccine Effectiveness against Hospitalization in Older Adults. N Engl J Med. 2025 Dec 11;393(23):2291-2302. doi: 10.1056/NEJMoa2509907. Epub 2025 Aug 30.
• Johansen ND, Modin D, Loiacono MM, Harris RC, Dufournet M, Larsen CS, Larsen L, Wiese L, Dalager-Pedersen M, Claggett BL, Janstrup KH, Bartholdy KV, Bernholm KF, Borchsenius JIH, Davidovski FS, Davodian LW, Dons M, Duus LS, Espersen C, Fussing FH, Jensen AMR, Landler NE, Langhoff ACF, Lassen MCH, Nielsen AB, Ottosen CI, Sengelov M, Skaarup KG, Pareek M, Solomon SD, Landray MJ, Gislason GH, Kober L, Sivapalan P, Martel CJ, Jensen JUS, Biering-Sorensen T. High-Dose vs Standard-Dose Influenza Vaccine and Cardiovascular Outcomes in Older Adults: A Prespecified Secondary Analysis of the DANFLU-2 Randomized Clinical Trial. JAMA Cardiol. 2025 Nov 1;10(11):1186-1194. doi: 10.1001/jamacardio.2025.3460.
• Skaarup KG, Johansen ND, Modin D, Loiacono MM, Harris RC, Dufournet M, Larsen CS, Larsen L, Wiese L, Dalager-Pedersen M, Claggett BL, Bartholdy KV, Bernholm KF, Borchsenius JIH, Davidovski FS, Davodian LW, Dons M, Duus LS, Espersen C, Fussing FH, Jensen AMR, Landler NE, Langhoff ACF, Lassen MCH, Nielsen AB, Ottosen CI, Sengelov M, Solomon SD, Landray MJ, Gislason GH, Kober L, Sivapalan P, Martel CJ, Jensen JUS, Mebazaa A, Biering-Sorensen T. High-Dose Versus Standard-Dose Influenza Vaccine in Heart Failure: A Prespecified Analysis of the DANFLU-2 Trial. Circ Heart Fail. 2025 Nov;18(11):e013678. doi: 10.1161/CIRCHEARTFAILURE.125.013678. Epub 2025 Aug 30.
• Davidovski FS, Skaarup KG, Johansen ND, Modin D, Shaikh N, Bartelt-Hofer J, Loiacono MM, Harris RC, Larsen CS, Larsen L, Wiese L, Dalager-Pedersen M, Jessen R, Steenhard N, Claggett BL, Solomon SD, Kober L, Sivapalan P, Jensen JUS, Martel CJ, Biering-Sorensen T. Patient-reported outcomes and home-based self-swabs for influenza-like illness events - lessons learned from the 2023/2024 DANFLU-2 Homeswab PRO substudy. J Patient Rep Outcomes. 2025 Aug 22;9(1):108. doi: 10.1186/s41687-025-00936-8.
• Johansen ND, Modin D, Loiacono MM, Harris RC, Dufournet M, Larsen CS, Larsen L, Wiese L, Dalager-Pedersen M, Claggett BL, Skaarup KG, Davidovski FS, Solomon SD, Landray MJ, Gislason GH, Kober L, Sivapalan P, Martel CJ, Jensen JUS, Biering-Sorensen T. A pragmatic individually randomized trial to evaluate the effectiveness of high-dose vs standard-dose influenza vaccine in older adults: Rationale and design of the DANFLU-2 trial. Am Heart J. 2026 Jan;291:186-198. doi: 10.1016/j.ahj.2025.07.069. Epub 2025 Jul 30.

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