Nationwide Utilization of Danish Government Electronic Letter System for Confirming the Effectiveness of Behavioral Nudges in Increasing InFLUenza Vaccine Uptake Among Older Adults (NUDGE-FLU-2)
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ClinicalTrials.gov Identifier: NCT06030726 |
Recruitment Status :
Recruiting
First Posted : September 11, 2023
Last Update Posted : September 21, 2023
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Condition or disease | Intervention/treatment | Phase |
---|---|---|
Influenza Behavior and Behavior Mechanisms | Behavioral: Behavioral Economic Principles | Not Applicable |
Study Type : | Interventional (Clinical Trial) |
Estimated Enrollment : | 1000000 participants |
Allocation: | Randomized |
Intervention Model: | Parallel Assignment |
Masking: | None (Open Label) |
Primary Purpose: | Other |
Official Title: | Nationwide Utilization of Danish Government Electronic Letter System for Confirming the Effectiveness of Behavioral Nudges in Increasing InFLUenza Vaccine Uptake Among Older Adults |
Estimated Study Start Date : | September 15, 2023 |
Estimated Primary Completion Date : | January 1, 2024 |
Estimated Study Completion Date : | May 31, 2024 |

Arm | Intervention/treatment |
---|---|
No Intervention: Usual Care
No letter
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Experimental: Standard Letter
This group will receive a standard letter on the benefits of influenza vaccination without behavioral economic enhancement
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Behavioral: Behavioral Economic Principles
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. |
Experimental: Repeated Letter
The standard letter sent out two times instead of once
|
Behavioral: Behavioral Economic Principles
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. |
Experimental: Cardiovascular Gain-Framing Letter
Text added to the standard letter highlighting potential cardiovascular benefits of influenza vaccination
|
Behavioral: Behavioral Economic Principles
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. |
Experimental: Respiratory Gain-Framing Letter
Text added to the standard letter highlighting potential respiratory disease-related benefits of influenza vaccination
|
Behavioral: Behavioral Economic Principles
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. |
Experimental: Implementation Intention Prompt Letter
Implementation intention prompt added to the standard letter
|
Behavioral: Behavioral Economic Principles
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. |
Experimental: Loss-Framing Letter
Text added to the standard letter highlighting potential risks of not receiving influenza vaccination
|
Behavioral: Behavioral Economic Principles
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. |
- Number of participants who received an influenza vaccine [ Time Frame: Up to 3 months ]
- Time from intervention delivery to influenza vaccination [ Time Frame: Up to 3 months ]
- Number of participants with laboratory-confirmed influenza [ Time Frame: Up to 8 months ]
- Number of participants with a hospitalization for influenza or pneumonia [ Time Frame: Up to 8 months ]
- Number of participants with a hospitalization for any respiratory disease [ Time Frame: Up to 8 months ]
- Number of participants with a hospitalization for any cardio-respiratory disease [ Time Frame: Up to 8 months ]
- Number of participants with a hospitalization for any cardiovascular disease [ Time Frame: Up to 8 months ]
- Number of participants with any hospitalization [ Time Frame: Up to 8 months ]
- Total number of hospitalizations (first and recurrent) [ Time Frame: Up to 8 months ]
- All-cause mortality [ Time Frame: Up to 8 months ]
- Composite of incident heart failure, heart failure hospitalization, or cardiovascular death [ Time Frame: Up to 8 months ]
- Composite of myocardial infarction, stroke, or cardiovascular death [ Time Frame: Up to 8 months ]
- Composite of myocardial infarction, coronary revascularization, stroke, or cardiovascular death [ Time Frame: Up to 8 months ]
- Number of participants with incident heart failure or heart failure hospitalization [ Time Frame: Up to 8 months ]
- Total number of heart failure events (incident heart failure and first and recurrent heart failure hospitalizations) [ Time Frame: Up to 8 months ]
- Cardiovascular death [ Time Frame: Up to 8 months ]
- Number of participants with myocardial infarction [ Time Frame: Up to 8 months ]
- Number of participants with coronary revascularization [ Time Frame: Up to 8 months ]
- Number of participants with stroke [ Time Frame: Up to 8 months ]
- Number of participants with incident atrial fibrillation or atrial fibrillation hospitalization [ Time Frame: Up to 8 months ]
- Number of contacts to general practitioner (excluding vaccination visit) [ Time Frame: Up to 8 months ]
- Number of participants with laboratory-confirmed COVID-19 [ Time Frame: Up to 8 months ]
- Number of participants with a hospitalization for COVID-19 [ Time Frame: Up to 8 months ]
- Number of participants who received a COVID-19 vaccine [ Time Frame: Up to 3 months ]
- Number of participants who filled a prescription for any guideline-directed medical therapy for heart failure [ Time Frame: Up to 8 months ]
- Total number of filled prescriptions for guideline-directed medical therapy for heart failure [ Time Frame: Up to 8 months ]
- Number of participants who filled a prescription for a sodium-glucose cotransporter 2 inhibitor or glucagon-like peptide 1 receptor agonist [ Time Frame: Up to 8 months ]

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Ages Eligible for Study: | 65 Years and older (Older Adult) |
Sexes Eligible for Study: | All |
Accepts Healthy Volunteers: | Yes |
Inclusion Criteria:
- 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
Exclusion Criteria:
- 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

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT06030726
Contact: Niklas Dyrby Johansen, MD | +4520204794 | niklas.dyrby.johansen@regionh.dk |
Denmark | |
Center for Translational Cardiology and Pragmatic Randomized Trials, Department of Cardiology, Copenhagen University Hospital - Herlev and Gentofte | Recruiting |
Hellerup, Hovedstaden, Denmark, 2900 | |
Contact: Niklas Dyrby Johansen, MD +4520204794 niklas.dyrby.johansen@regionh.dk | |
Contact: Tor Biering-Sørensen, MD, MSc, MPH, PhD +4528933590 tor.biering-soerensen@regionh.dk | |
Principal Investigator: Tor Biering-Sørensen, MD, MSc, MPH, PhD |
Principal Investigator: | Tor Biering-Sørensen, MD, MSc, MPH, PhD | Center for Translational Cardiology and Pragmatic Randomized Trials, Department of Cardiology, Copenhagen University Hospital - Herlev and Gentofte |
Responsible Party: | Tor Biering-Sørensen, Professor, MD, MSc, MPH, PhD, Herlev and Gentofte Hospital |
ClinicalTrials.gov Identifier: | NCT06030726 |
Other Study ID Numbers: |
NUDGE-FLU-2 |
First Posted: | September 11, 2023 Key Record Dates |
Last Update Posted: | September 21, 2023 |
Last Verified: | September 2023 |
Individual Participant Data (IPD) Sharing Statement: | |
Plan to Share IPD: | Yes |
Plan Description: | 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. |
Studies a U.S. FDA-regulated Drug Product: | No |
Studies a U.S. FDA-regulated Device Product: | No |
Influenza Vaccination Nudging Behavioral Science |
Influenza, Human Respiratory Tract Infections Infections Orthomyxoviridae Infections |
RNA Virus Infections Virus Diseases Respiratory Tract Diseases |