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CompletedNCT04590066Updated Feb 1, 2021

Testing Multiple Behavioral Science Strategies to Increase Flu-Shot Rates at a Large Retail Pharmacy

An interventional study of Flu shot text messages in Influenza, Human, sponsored by University of Pennsylvania. Completed at 1 site in United States. Open to participants aged 18 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2021-02-01.

Sponsored by University of Pennsylvania · Not applicable, Interventional, and Health services research

Phase
Not applicable
Study type
Interventional
Enrollment
734,383
Allocation
Randomized
Ages
18 Years and older
Sex
All
01

Study summary

This research aims to identify which behavioral science strategies are most effective at increasing flu vaccination rates overall and based on patients' individual characteristics. Past behavioral science interventions have shown promise in increasing flu vaccinations. For example, successful interventions have encouraged people to make concrete plans for when they will get a flu vaccination, sent automated calls or text messages reminding patients to get a flu vaccination , or provided financial incentives for getting vaccinated. Although these results are promising, these studies have been conducted in isolation on different populations, which makes it difficult to compare their interventions' effectiveness or to have enough power to reliably detect differing responses to interventions based on individual characteristics.

This research will simultaneously test 22 different SMS interventions to increase flu vaccinations compared to a holdout control condition in a "mega-study" and apply machine learning to identify which interventions work best for whom. The interventions are designed by behavioral science experts from the Behavior Change for Good Initiative (BCFG), Penn Medicine Nudge Unit (PMNU), and Geisinger Behavioral Insights Team (BIT). Customers of a large retail pharmacy who received a flu shot from the pharmacy last year and receive SMS notifications will be included in this study. We expect this to include approximately 1.2 million participants.

The specific aims of this research are to identify (1) which behavioral science strategies effectively increase flu vaccination rates overall, and (2) which strategies are most effective for different subgroups (e.g., based on age, gender, race).

02

Conditions studied

  • Influenza, Human

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Keywords

  • Influenza vaccination
  • behavioral science interventions
  • vaccination promotion
03

In context

Influenza, Human

2,214 studies on the registry are indexed under Influenza, Human; 164 are open to participants now.

This study's enrollment of 734,383 is above the median of 238 across 1,853 interventional studies indexed under Influenza, Human.

Browse Influenza, Human studies →

Lead sponsor

University of Pennsylvania is the lead sponsor of 1,635 studies on the registry; 239 are open to participants now.

Of its 154 completed or terminated interventional studies of FDA-regulated products, 104 (68%) have results posted.

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
18 Years and older
Sexes eligible
All
Accepts healthy volunteers
Yes

Inclusion criteria

  1. Have agreed to receive SMS messages from the pharmacy
  2. Received a flu shot from the pharmacy in the 2019-2020 flu season, as documented in their pharmacy records.

Exclusion criteria

Exclusion Criteria:

-

05

Study design

Phase
Not applicable
Primary purpose
Health services research
Allocation
Randomized
Intervention model
Parallel assignment
Masking
Double (Care provider, Outcomes assessor)
Enrollment
734,383 participants (actual)

Study arms

  • No intervention
    Holdout control

    Participants will only receive the standard pharmacy messaging.

  • Experimental
    Unpacking Risks Treatment

    Participants will be asked to think about the risks of catching the flu this flu season and to respond with the location they are most likely to catch the flu out of a list of given options (e.g. at work, at home).

    Behavioral: Flu shot text messages

  • Experimental
    Unpacking Risks Control

    Participants will be asked to think about the risks of catching the flu this flu season and to respond to confirm that they have received the message.

    Behavioral: Flu shot text messages

  • Experimental
    Active Commitment Treatment

    Participants receive a gain framed notification that they are eligible for a flu shot. In addition, participants are told "Many people find it helpful to make a plan to get their shot" and are asked to commit by texting back "I will get a flu shot." Depending on their response, participants receive a general reminder or a commitment reminder 3 days later.

    Behavioral: Flu shot text messages

  • Experimental
    Active Commitment Control

    Participants receive a gain framed notification that they are eligible for a flu shot. Participants receive a general reminder 3 days later.

    Behavioral: Flu shot text messages

  • Experimental
    Self-Generated Social Norms Treatment

    Participants will first receive a message enjoining them to consider 2 peers who would want them to vaccinate. Then they will be asked to do those peers a favor by getting a vaccine at their next opportunity. They will receive a reminder 3 days later.

    Behavioral: Flu shot text messages

  • Experimental
    Self-Generated Social Norms Control

    articipants will be informed of the opportunity to receive a flu vaccine at their appointment. They will receive a reminder 3 days later.

    Behavioral: Flu shot text messages

  • Experimental
    Foot-in-the-Door Treatment

    Participants will first receive a message enjoining them to encourage someone else to receive a flu vaccine this year. They will then be given a message that they might copy-paste to forward to friends, thereby lowering the effort costs of messaging others. They will receive a reminder 3 days later.

    Behavioral: Flu shot text messages

  • Experimental
    Foot-in-the-Door Control

    Participants will be informed of the opportunity to receive a flu vaccine at their appointment. They will receive a reminder 3 days later.

    Behavioral: Flu shot text messages

  • Experimental
    Prosocial Condition

    Participants will receive a message describing the condition-specific benefit of getting a flu shot, and a reminder to ask for their flu shot. The message will also give prosocial reasons for vaccinating (i.e., protecting loved ones; preserving scarce resources).

    Behavioral: Flu shot text messages

  • Experimental
    Self-Oriented Condition

    Participants will receive a message describing the condition-specific benefit of getting a flu shot, and a reminder to ask for their flu shot.

    Behavioral: Flu shot text messages

  • Experimental
    Prosocial + COVID-19

    Participants will receive a message describing the condition-specific benefit of getting a flu shot, and a reminder to ask for their flu shot. The message will also give prosocial reasons for vaccinating (e.g., protecting loved ones; preserving scarce resources). The message will also emphasize the pandemic (e.g., risk of hospital-acquired COVID-19 infection; wasting scarce resources).

    Behavioral: Flu shot text messages

  • Experimental
    Self-Oriented + COVID-19

    Participants will receive a message describing the condition-specific benefit of getting a flu shot, and a reminder to ask for their flu shot. The message will also emphasize the pandemic (e.g., risk of hospital-acquired COVID-19 infection; wasting scarce resources).

    Behavioral: Flu shot text messages

  • Experimental
    Dynamic + Static Norm

    Participants will receive a text message encouraging them to get a flu shot and informing them that more American adults are getting their flu shot than ever before and how many Americans got their flu shot last year.

    Behavioral: Flu shot text messages

  • Experimental
    Dynamic Norm

    Participants will receive a text message encouraging them to get a flu shot and informing them that more American adults are getting their flu shot than ever before.

    Behavioral: Flu shot text messages

  • Experimental
    Dynamic Norms Control

    Participants will only receive a text message encouraging them to get a flu shot. They will not receive any norm information.

    Behavioral: Flu shot text messages

  • Experimental
    Sharing Humor

    Participants will receive a text message encouraging them to get the flu shot. The message will include a joke about the flu and will encourage participants to share the joke with nurses, doctors, or pharmacists.

    Behavioral: Flu shot text messages

  • Experimental
    Humor Placebo

    Participants will receive a text message encouraging them to get the flu shot. This message will include the same joke but participants will not be encouraged to share it.

    Behavioral: Flu shot text messages

  • Experimental
    No Humor Condition

    Participants will receive a text message encouraging them to get the flu shot.

    Behavioral: Flu shot text messages

  • Experimental
    Connecting the Past Self to the Future Self Treatment

    Participants will receive a text message prompt to recall the negative experience of getting sick. When asked, "Do you wish you could have avoided getting sick by getting a simple shot?", participants will have the chance to respond Y for yes or N for no. Regardless of their response, they will be prompted with a second text message to connect their past experience with present-day opportunities for preventative care (getting a flu shot) to protect the future self from the flu.

    Behavioral: Flu shot text messages

  • Experimental
    Connecting the Past Self to the Future Self Control

    In the first text message, participants will receive a simple text message encouragement to receive a flu shot. In the second text message, they will receive a reminder of the appointment time and provider name.

    Behavioral: Flu shot text messages

  • Experimental
    Reverse Inference Condition

    Participants will receive a text message encouraging them to get a flu shot and informing them that Americans who get flu shots are healthier, wealthier, and more educated.

    Behavioral: Flu shot text messages

  • Experimental
    Reverse Inference Control Condition

    Participants will receive a text message encouraging them to get a flu shot and informing them that Americans who get flu shots are less likely to get the flu.

    Behavioral: Flu shot text messages

Interventions

  • BehavioralFlu shot text messages

    Participants will receive text messages per descriptions listed in the arms.

06

What researchers measure

Primary outcomes

  1. Whether participants receive a flu shot vaccination at our pharmacy partner by December 31, 2020

    The primary outcome measure is whether participants receive a flu shot at our retail pharmacy partner by December 31, 2020 (as recorded in their pharmacy records) after receiving the SMS intervention on September 25, 2020. Participants who receive a flu shot before September 25, 2020 when they received the SMS intervention will be excluded from the analyses.

    Time frame: 98 days

Secondary outcomes

  1. Whether participants receive a flu shot vaccination at our pharmacy partner by October 31, 2020

    The secondary outcome measure is whether participants receive a flu shot at our retail pharmacy partner by October 31, 2020 (as recorded in their pharmacy records) after receiving the SMS intervention on September 25, 2020. Participants who receive a flu shot before they receive the SMS intervention on September 25, 2020 will be excluded from the analyses.

    Time frame: 37 days

07

Study locations

1 site
  • University of Pennsylvania
    Philadelphia, Pennsylvania 19104, United States
08

References and documents

Publications

  • Cutrona SL, Golden JG, Goff SL, Ogarek J, Barton B, Fisher L, Preusse P, Sundaresan D, Garber L, Mazor KM. Improving Rates of Outpatient Influenza Vaccination Through EHR Portal Messages and Interactive Automated Calls: A Randomized Controlled Trial. J Gen Intern Med. 2018 May;33(5):659-667. doi: 10.1007/s11606-017-4266-9. Epub 2018 Jan 30. PubMed 29383550 ↗
  • Milkman KL, Beshears J, Choi JJ, Laibson D, Madrian BC. Using implementation intentions prompts to enhance influenza vaccination rates. Proc Natl Acad Sci U S A. 2011 Jun 28;108(26):10415-20. doi: 10.1073/pnas.1103170108. Epub 2011 Jun 13. PubMed 21670283 ↗
  • Regan AK, Bloomfield L, Peters I, Effler PV. Randomized Controlled Trial of Text Message Reminders for Increasing Influenza Vaccination. Ann Fam Med. 2017 Nov;15(6):507-514. doi: 10.1370/afm.2120. PubMed 29133488 ↗
  • Nowalk MP, Lin CJ, Toback SL, Rousculp MD, Eby C, Raymund M, Zimmerman RK. Improving influenza vaccination rates in the workplace: a randomized trial. Am J Prev Med. 2010 Mar;38(3):237-46. doi: 10.1016/j.amepre.2009.11.011. Epub 2009 Dec 24. PubMed 20036102 ↗

Individual participant data

Plan to share: No

09

Updates

Tracking since Sep 25, 2026
No changes since tracking began. The registry record was last updated on Feb 1, 2021, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
10

Registry details

Key details

Study ID
NCT04590066
Lead sponsor
University of Pennsylvania
Responsible party
Sponsor
First posted
Oct 19, 2020
Start date
Sep 25, 2020
Primary completion
Dec 31, 2020
Completion
Dec 31, 2020
Last update
Feb 1, 2021

Oversight

Data monitoring committee
Yes
FDA-regulated drug
No
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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This study is completed, as verified in Jan 2021. You cannot join it, but the record below documents what was studied.

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