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NCT06600490

Nationwide Utilization of Danish Government Electronic Letter System for Confirming the Effectiveness of Behavioral Nudges in Increasing InFLUenza Vaccine Uptake Among Adults With Chronic Disease

Completed NA Last updated 12 September 2025
What this trial tests

NA trial testing Behavioral Economic Principles in Influenza in 308,978 participants. Completed in 31 May 2025.

Timeline
1 October 2024
Primary endpoint
1 January 2025
31 May 2025

Quick facts

Lead sponsorTor Biering-Sørensen
PhaseNA
StatusCompleted
Study typeINTERVENTIONAL
Allocationrandomized
Designparallel
Maskingnone
Primary purposeother
Enrollment308,978
Start date1 October 2024
Primary completion1 January 2025
Estimated completion31 May 2025
Sites1 location across Denmark

Drugs / interventions tested

Conditions studied

Sponsor

Tor Biering-Sørensen — full company profile →

Who can join

Adults 18 to 64, any sex, with Influenza or Behavior and Behavior Mechanisms. Patients with the condition only — healthy volunteers not accepted.

Sponsor's own description

In randomized clinical trials and observational studies, influenza vaccination has been shown to be effective in reducing influenza-related illness, hospitalizations, cardiovascular events, and mortality in select populations. However, the real-world effectiveness of influenza vaccination is limited by its uptake. Conducted during the 2023/2024 influenza season, the first NUDGE-FLU-CHRONIC trial demonstrated the effectiveness of behavioral nudging letters in increasing influenza vaccination rates among adults aged 18-64 years with chronic diseases in Denmark. This present study will once again investigate whether digital behavioral nudges delivered via the official, mandatory Danish electronic letter system can increase influenza vaccine uptake among adults aged 18-64 years with chronic diseases including whether the effectiveness of the previously successful strategies can be confirmed during a subsequent influenza season.

Publications & conference data

1 peer-reviewed publication reference this trial (live from Europe PMC):

  1. Digital Nudges to Increase Influenza Vaccination in Patients with Chronic Diseases.
    Johansen ND, Vaduganathan M, Bhatt AS, Modin D, et al · · 2026 · cited 1× · PMID 41213006 · DOI 10.1056/evidoa2500265

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Other trials of Behavioral Economic Principles

Trials testing the same drug.

Other recruiting trials for Influenza

Currently open trials in the same condition.

Other Tor Biering-Sørensen trials

Trials by the same sponsor.

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Data sources for this page

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