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InfluenzaNUDGE-FLU-2NCT06030726

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

A study testing Behavioral Economic Principles in people with Influenza and Behavior and Behavior Mechanisms, run by Tor Biering-Sørensen at 1 site in Denmark.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record
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Trial summary

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. Read more about this study

Who is it for?
Ages 65 years and olderHealthy volunteers can take part
Conditions the study is for
Influenza, Behavior and Behavior Mechanisms
What is being tested?
Behavioral Economic Principles
Could I receive a placebo?
No, everyone receives an active treatment
How many people
881,373 participants
Where
1 siteDenmark
Study dates
14 Sep 2023to 31 May 2024
Phase
Interventional
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
  • Healthy volunteers accepted
  • Older adult

Who may be able to join

  • Age >=65 years at January 15, 2024 (eligible for free-of-charge influenza vaccination in the Danish public health system)
  • Access to the official, mandatory Danish electronic mailbox system

Who cannot join

  • Persons living in nursing homes (approximated as any person living at an address with >=6 inhabitants aged 80 years and above)
  • Known to have already scheduled influenza vaccination appointment

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

Other trials in Denmark

About this study

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 2022/2023 influenza season, the first NUDGE-FLU trial demonstrated the effectiveness of two electronic behavioral nudging letter strategies in increasing influenza vaccination rates among older adults in Denmark - a letter highlighting potential cardiovascular benefits of vaccination and a standard informational letter sent at baseline and repeated at day 14. 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 older adults including whether the effectiveness of previously successful strategies can be confirmed during a subsequent influenza season.

Read the detailed description

The study is a prospective, randomized, open-label implementation trial. The study population will consist of persons aged >=65 years at January 15, 2024 - this age group is eligible for free-of-charge influenza vaccination in the official Danish vaccination program. Subjects will be identified through Danish nationwide health registries including the Danish Civil Registration System. Individuals will be randomized to 1 of 7 arms (1 usual care arm and 6 intervention arms) with each testing different nudging strategies employing various behavioural economic principles. The interventions will be delivered through the official, mandatory Danish electronic letter system. All subject data will be retrieved from the Danish nationwide registries with the exception of information on intervention allocation. Endpoints will be retrieved at prespecified dates using prespecified search algorithms.

Being tested
Behavioral Economic Principles
Keywords
Influenza, Vaccination, Nudging, Behavioral Science
Medical subject headings
Influenza, Human, Behavior

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • Behavioral Economic PrinciplesBehavioural

    The control arm will receive no letter to reflect the background vaccination uptake. Intervention arms will test the effects of different letters developed using behavioral economic principles.

Study groups in NCT06030726
Study groupRoleWhat they receive
Usual CareNo interventionNo letter
Standard LetterExperimentalThis group will receive a standard letter on the benefits of influenza vaccination without behavioral economic enhancement
Receives: Behavioral: Behavioral Economic Principles
Repeated LetterExperimentalThe standard letter sent out two times instead of once
Receives: Behavioral: Behavioral Economic Principles
Cardiovascular Gain-Framing LetterExperimentalText added to the standard letter highlighting potential cardiovascular benefits of influenza vaccination
Receives: Behavioral: Behavioral Economic Principles
Respiratory Gain-Framing LetterExperimentalText added to the standard letter highlighting potential respiratory disease-related benefits of influenza vaccination
Receives: Behavioral: Behavioral Economic Principles
Implementation Intention Prompt LetterExperimentalImplementation intention prompt added to the standard letter
Receives: Behavioral: Behavioral Economic Principles
Loss-Framing LetterExperimentalText added to the standard letter highlighting potential risks of not receiving influenza vaccination
Receives: Behavioral: Behavioral Economic Principles

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Number of participants who received an influenza vaccine

    Measured: Up to 3 months

Secondary outcomes (1)

  1. Time from intervention delivery to influenza vaccination

    Measured: Up to 3 months

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted11 Sep 2023
  2. Study start14 Sep 2023
  3. Primary completion1 Jan 2024
  4. Study completion31 May 2024

Resources

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 N/A
Primary purpose
Other
Allocation
Randomised
Intervention model
Parallel groups
Masking
None (open label)
Enrolment
881,373 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT06030726
Sponsor's protocol ID
NUDGE-FLU-2
Acronym
NUDGE-FLU-2
Status last verified
Oct 2024
First submitted
31 Aug 2023
Last updated
10 Oct 2024
Results posted
No
Data monitoring committee
No
FDA-regulated drug
No
FDA-regulated device
No
Individual data sharing
Yes: Data will be collected from Danish administrative health registries, which are subject to Danish legislation and can only be made available to a third party under certain conditions. Please contact the sponsor-investigator in case of any inquiries.

Publications

  • Reimer Jensen AM, Johansen ND, Wolff PS, Vaduganathan M, Bhatt AS, Modin D, Skaarup KG, Duus LS, Chatur S, Claggett BL, Janstrup KH, Hill JA, Van Spall HGC, Larsen CS, Larsen L, Wiese L, Dalager-Pedersen M, Kober L, Solomon SD, Sivapalan P, Jensen JUS, Martel CJ, Krause TG, Biering-Sorensen T. Electronic Nudges to Increase Influenza Vaccination in Immunosuppressed Adults Across the Age Spectrum: A Pooled Analysis of 2 Nationwide Randomized Trials. Clin Infect Dis. 2026 Sep 2;83(2):321-330. doi: 10.1093/cid/ciag219.

    PubMed 41968745

  • Bhatt AS, Johansen ND, Vaduganathan M, Modin D, Pareek M, Chatur S, Claggett BL, Janstrup KH, Larsen CS, Larsen L, Wiese L, Dalager-Pedersen M, Dueger EL, Samson S, Loiacono MM, Harris RC, Kober L, Solomon SD, Martel CJ, Sivapalan P, Jensen JUS, Biering-Sorensen T. Electronic Nudges and Influenza Vaccination Among Patients With a History of Myocardial Infarction: Insights From 3 Nationwide Randomized Clinical Trials. JAMA Cardiol. 2025 Jan 1;10(1):78-86. doi: 10.1001/jamacardio.2024.4648.

    PubMed 39550717

  • Johansen ND, Vaduganathan M, Bhatt AS, Modin D, Chatur S, Claggett BL, Janstrup KH, Larsen CS, Larsen L, Wiese L, Dalager-Pedersen M, Kober L, Solomon SD, Sivapalan P, Jensen JUS, Martel CJ, Krause TG, Biering-Sorensen T. Electronic nudges for sustained influenza vaccination uptake in older adults: the nationwide randomized NUDGE-FLU-2 trial. Nat Med. 2024 Nov;30(11):3142-3149. doi: 10.1038/s41591-024-03202-4. Epub 2024 Aug 30.

    PubMed 39215149

  • Johansen ND, Vaduganathan M, Bhatt AS, Modin D, Chatur S, Claggett BL, Janstrup KH, Larsen CS, Larsen L, Wiese L, Dalager-Pedersen M, Kober L, Solomon SD, Sivapalan P, Jensen JUS, Martel CJ, Krause TG, Biering-Sorensen T. Rationale and design of NUDGE-FLU-CHRONIC and NUDGE-FLU-2: Two nationwide randomized trials of electronic nudges to increase influenza vaccination among patients with chronic diseases and older adults during the 2023/2024 influenza season. Am Heart J. 2024 Jun;272:23-36. doi: 10.1016/j.ahj.2024.03.003. Epub 2024 Mar 7.

    PubMed 38460754

Questions about this trial

What is this clinical trial studying?

A study testing Behavioral Economic Principles in people with Influenza and Behavior and Behavior Mechanisms, 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 2 inclusion and 2 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 10 Oct 2024. 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.

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?

Number of participants who received an influenza vaccine (time frame: Up to 3 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 NCT06030726, which also lists 4 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 10 Oct 2024.

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