Brief 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 (Milkman et al. 2011), sent automated calls or text messages reminding patients to get a flu vaccination (Cutrona et al. 2018; Regan et al. 2017), or provided financial incentives for getting vaccinated (Nowalk et al. 2010). 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 19 different SMS interventions to increase flu vaccinations 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). We expect to include at least 80,000 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).

Trial Health

On Track

Trial Health Score

Automated assessment based on enrollment pace, timeline, and geographic reach

Enrollment

74,811

participants targeted

Target at P75+ for not_applicable

Timeline

Completed

Started Sep 2020

Shorter than P25 for not_applicable

Geographic Reach

1 country

2 active sites

Status

completed

Health score is calculated from publicly available data and should be used for screening purposes only.

Trial Relationships

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Study Timeline

Key milestones and dates

6 months study duration

First Submitted

Initial submission to the registry

September 10, 2020

Completed

10 days until next milestone

Study Start

First participant enrolled

September 20, 2020

Completed

5 days until next milestone

First Posted

Study publicly available on registry

September 25, 2020

Completed

6 months until next milestone

Primary Completion

Last participant's last visit for primary outcome

March 31, 2021

Completed

Same day until next milestone

Study Completion

Last participant's last visit for all outcomes

March 31, 2021

Completed

4 months until next milestone

Results Posted

Study results publicly available

August 11, 2021

Completed

Last Updated

February 1, 2022

Status Verified

January 1, 2022

Enrollment Period

6 months

First QC Date

September 10, 2020

Results QC Date

June 14, 2021

Last Update Submit

January 25, 2022

Conditions

Influenza, Human

Keywords

Influenza vaccinationbehavioral science interventionsvaccination promotion

Outcome Measures

Primary Outcomes (1)

Number of Participants With Flu Shot Receipt at or Before Appointment
Our field experiment will be conducted with Penn Medicine and Geisinger Health patients via SMS messages sent prior to their first primary care appointment during the study period, hereafter referred to as the "target appointment." The key dependent variable is whether participants receive a flu shot at or before their target appointment (as recorded in their electronic health records). If participants cancel or do not show up for their target appointment after they have been randomized to a treatment and then schedule a new appointment during the study period, their new primary care appointment becomes the target appointment. Participants who have been randomized to a treatment will be counted as not having received a flu shot if they cancel or do not show up for their target appointment and do not schedule a new appointment during the study period. Participants who receive a flu shot before they receive the SMS intervention will be excluded from the analyses.
The dependent variable will be assessed during a 4-day period after randomization starting three days prior to the participant's target primary care appointment through the date of the target appointment (including the date of the appointment)

Secondary Outcomes (1)

Number of Participants With Flu Shot Receipt Before March 31, 2021
Up to 6 months after randomization.

Study Arms (20)

Holdout control

NO INTERVENTION

Participants will only receive the standard appointment reminders from their providers.

Default Reservations Opt-Out Condition

EXPERIMENTAL

The day before their scheduled appointment, participants receive a text reading: "A flu shot has been reserved for you to receive at your appointment tomorrow. Reply Y if you want this shot held for you, N if you don't." The text will include a picture of a vial that says "Your Flu Shot" on it.