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)

Tor Biering-Sørensen

Status: Completed

Conditions: Influenza; Behavior and Behavior Mechanisms

Treatments: Behavioral: Behavioral Economic Principles

Study type: Interventional

Funder types: Other

Identifiers

NCT06030726

NUDGE-FLU-2

Details and patient eligibility

About

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.

Full 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.

Enrollment: 881,373 patients

Sex: All

Ages: 65+ years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

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

Exclusion criteria

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

Trial design

Primary purpose: Other

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: None (Open label)

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881,373 participants in 7 patient groups

Usual Care

No Intervention group

Description:

No letter

Standard Letter

Experimental group

Description:

This group will receive a standard letter on the benefits of influenza vaccination without behavioral economic enhancement

Treatment:

Behavioral: Behavioral Economic Principles

Repeated Letter

Experimental group

Description:

The standard letter sent out two times instead of once

Treatment:

Behavioral: Behavioral Economic Principles

Cardiovascular Gain-Framing Letter

Experimental group

Description:

Text added to the standard letter highlighting potential cardiovascular benefits of influenza vaccination

Treatment:

Behavioral: Behavioral Economic Principles

Respiratory Gain-Framing Letter

Experimental group

Description:

Text added to the standard letter highlighting potential respiratory disease-related benefits of influenza vaccination

Treatment:

Behavioral: Behavioral Economic Principles

Implementation Intention Prompt Letter

Experimental group

Description:

Implementation intention prompt added to the standard letter

Treatment:

Behavioral: Behavioral Economic Principles

Loss-Framing Letter

Experimental group

Description:

Text added to the standard letter highlighting potential risks of not receiving influenza vaccination

Treatment:

Behavioral: Behavioral Economic Principles