An interventional study of Flu shot text messages in Influenza, Human, sponsored by University of Pennsylvania. Completed at 2 sites in United States. Open to participants aged 18 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2022-02-01.
Sponsored by University of Pennsylvania · Not applicable, Interventional, and Health services research
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).
2,214 studies on the registry are indexed under Influenza, Human; 164 are open to participants now.
This study's enrollment of 74,811 is above the median of 238 across 1,853 interventional studies indexed under Influenza, Human.
Browse Influenza, Human studies →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.
Penn Medicine and Geisinger patients will be included if they:
Inclusion Criteria:
Exclusion Criteria:
We will recruit as many patients as possible starting in September 2020. We will stop enrolling participants with appointments scheduled to occur after December 31, 2020 if we have reached 4,000 participants per condition. If we do not have 4,000 participants per condition by December 31, 2020, we will continue enrolling participants until we have reached 4,000 per condition, or until March 31, 2021 (discontinuing enrollment at whichever milestone arrives sooner - 4,000 people enrolled or 3/31/21).
Participants will only receive the standard appointment reminders from their providers.
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.
Behavioral: Flu shot text messages
The day before their scheduled appointment, participants receive a text reading: "Reply Y if you would like to receive a flu shot at your appointment tomorrow, N if not." The text will include a picture of vial with no text on it.
Behavioral: Flu shot text messages
Three days before their scheduled appointment, participants will receive a text message with information about how much "your region" lagged behind "another region" in flu shot rate last year ("your region" and "another region" will depend on the study site and include realistic flu shot rates based on historical CDC data). Participants will receive a reminder message on the day of the appointment.
Behavioral: Flu shot text messages
Three days before their scheduled appointment, participants will receive a text message with information about how much "your region" lagged behind the target flu shot rate of 70% last year ("your region" will depend on the study site and include realistic flu shot rates based on historical CDC data). Participants will receive a reminder message on the day of the appointment.
Behavioral: Flu shot text messages
Three days before their scheduled appointment, participants will receive a text message encouraging them to get a flu shot. They will also be told that they have the opportunity to dedicate getting the flu shot to someone by texting back the initials of an individual. Participants will receive a reminder message on the day of the appointment.
Behavioral: Flu shot text messages
Three days before their scheduled appointment, participants will receive a text message encouraging them to get a flu shot. They will also be told that they have the opportunity of getting the flu shot to protect a vulnerable loved one by texting back the initials of an individual. Participants will receive a reminder message on the day of the appointment.
Behavioral: Flu shot text messages
Three days before their scheduled appointment, participants will receive a text message encouraging them to get a flu shot. They will also receive a reminder message on the day of the appointment. They will not receive any further information, nor will they be asked to respond with initials of an individual.
Behavioral: Flu shot text messages
The day before their scheduled appointment, participants will receive a message describing the pro-social benefits of getting a flu shot, and a reminder to ask for their flu shot. The described pro-social benefits will vary whether they emphasize the COVID-19 pandemic (e.g., protecting loved ones from the risk of hospital-acquired COVID-19 infection) or not (e.g., protecting loved ones from serious complications from the flu). Participants will also receive a reminder message on the day of the appointment.
Behavioral: Flu shot text messages
The day before their scheduled appointment, participants will receive a message describing the self-oriented benefits of getting a flu shot, and a reminder to ask for their flu shot. The described self-oriented benefits will vary whether they emphasize the COVID-19 pandemic (e.g., protecting oneself from the risk of hospital-acquired COVID-19 infection) or not (e.g., protecting oneself from serious complications from the flu).
Behavioral: Flu shot text messages
Three days before their scheduled appointment, participants will receive a message inviting them to watch a 2-minute wellness video and answer some related questions, as well as encouragement to get the flu shot. In this condition, the video will contain vivid information about getting the flu. Participants will also receive a reminder message the day before the appointment.
Behavioral: Flu shot text messages
Three days before their scheduled appointment, participants will receive a message inviting them to watch a 2-minute wellness video and answer some related questions, as well as encouragement to get the flu shot. In this condition, the video will contain basic information about getting the flu. Participants will also receive a reminder message the day before the appointment.
Behavioral: Flu shot text messages
Three days before their scheduled appointment, participants will receive a message inviting them to watch a 2-minute wellness video and answer some related questions, as well as encouragement to get the flu shot. In this condition, the video will contain information about exercising. Participants will also receive a reminder message the day before the appointment.
Behavioral: Flu shot text messages
The day before their scheduled appointment, 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
The day before their scheduled appointment, participants will receive a text message encouraging them to get the flu shot.
Behavioral: Flu shot text messages
The day before their scheduled appointment, participants will be asked if they have completed a series of easy health behaviors (e.g., whether they walked 500 feet yesterday, at least two serving of fruits and vegetables in the last week, and slept at least 6 hours the previous night). They will then be encouraged to get a flu shot at their appointment.
Behavioral: Flu shot text messages
The day before their scheduled appointment, participants will be asked if they have completed a series of difficult health behaviors (e.g., whether they walked 3 miles yesterday, ate 4-6 servings of fruits and vegetables yesterday, and slept at least 9 hours the previous night). They will then be encouraged to get a flu shot at their appointment.
Behavioral: Flu shot text messages
The day before their scheduled appointment, participants will receive a text message encouraging them to get a flu shot.
Behavioral: Flu shot text messages
Seventy-two hours before their appointment, participants will receive a text message alerting them to the availability of the flu vaccine at their upcoming appointment. Participants will be told they'll receive a reminder, which they can opt-out from receiving. The text message reminder will be sent 24 hours before their appointment.
Behavioral: Flu shot text messages
Just-In-Time Reminders 15-Minute Condition: Seventy-two hours before their appointment, participants will receive a text message alerting them to the availability of the flu vaccine at their upcoming appointment. Participants will be told they'll receive a reminder, which they can opt-out from receiving. The text message reminder will be sent 15 minutes before their appointment.
Behavioral: Flu shot text messages
Participants will receive text messages per descriptions listed in the arms.
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.
Time frame: 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)
Number of Participants With Flu Shot Receipt Before March 31, 2021
The secondary dependent variable is whether participants receive the flu shot at or before their target appointment or at any time after this appointment (by March 31, 2021), as recorded in their electronic health records. Participants who receive a flu shot before they receive the SMS intervention will be excluded from the analyses.
Time frame: Up to 6 months after randomization.
| Milestone | Holdout Control | Default Reservations Opt-Out Condition | Default Reservations Opt-In Condition | Intergroup Competition Treatment Condition | Intergroup Competition Control Condition | Flu Shot for You Symbolic Condition | Flu Shot for You Herd Immunity Condition | Flu Shot for You Control Condition | Prosocial Condition | Self-Oriented Condition | Information Vivid Condition | Information Basic Condition | Information Control Condition | Sharing Humor Condition | No Humor Condition | Healthy Habits Easy Health Behavior Condition | Healthy Habits Difficult Health Behavior Condition | Healthy Habits Control Condition | Just-In-Time Reminders 24-Hour Condition | Just-In-Time Reminders 15-Minute Condition |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Started | 3742 | 3737 | 3709 | 3735 | 3758 | 3769 | 3719 | 3732 | 3728 | 3777 | 3672 | 3751 | 3737 | 3714 | 3773 | 3739 | 3776 | 3744 | 3741 | 3758 |
| Completed | 3742 | 3688 | 3670 | 3693 | 3717 | 3716 | 3665 | 3693 | 3662 | 3734 | 3623 | 3710 | 3685 | 3664 | 3736 | 3690 | 3734 | 3696 | 3698 | 3712 |
| Not completed | 0 | 49 | 39 | 42 | 41 | 53 | 54 | 39 | 66 | 43 | 49 | 41 | 52 | 50 | 37 | 49 | 42 | 48 | 43 | 46 |
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.
| Participants | Holdout Control | Default Reservations Opt-Out Condition | Default Reservations Opt-In Condition | Intergroup Competition Treatment Condition | Intergroup Competition Control Condition | Flu Shot for You Symbolic Condition | Flu Shot for You Herd Immunity Condition | Flu Shot for You Control Condition | Prosocial Condition | Self-Oriented Condition | Information Vivid Condition | Information Basic Condition | Information Control Condition | Sharing Humor Condition | No Humor Condition | Healthy Habits Easy Health Behavior Condition | Healthy Habits Difficult Health Behavior Condition | Healthy Habits Control Condition | Just-In-Time Reminders 24-Hour Condition | Just-In-Time Reminders 15-Minute Condition |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Number of Participants With Flu Shot Receipt at or Before Appointment | 1113 | 1210 | 1150 | 1163 | 1183 | 1200 | 1192 | 1191 | 1157 | 1224 | 1144 | 1231 | 1171 | 1135 | 1199 | 1181 | 1193 | 1130 | 1240 | 1227 |
The secondary dependent variable is whether participants receive the flu shot at or before their target appointment or at any time after this appointment (by March 31, 2021), as recorded in their electronic health records. Participants who receive a flu shot before they receive the SMS intervention will be excluded from the analyses.
| Participants | Holdout Control | Default Reservations Opt-Out Condition | Default Reservations Opt-In Condition | Intergroup Competition Treatment Condition | Intergroup Competition Control Condition | Flu Shot for You Symbolic Condition | Flu Shot for You Herd Immunity Condition | Flu Shot for You Control Condition | Prosocial Condition | Self-Oriented Condition | Information Vivid Condition | Information Basic Condition | Information Control Condition | Sharing Humor Condition | No Humor Condition | Healthy Habits Easy Health Behavior Condition | Healthy Habits Difficult Health Behavior Condition | Healthy Habits Control Condition | Just-In-Time Reminders 24-Hour Condition | Just-In-Time Reminders 15-Minute Condition |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Number of Participants With Flu Shot Receipt Before March 31, 2021 | 1296 | 1391 | 1330 | 1343 | 1338 | 1371 | 1369 | 1370 | 1360 | 1418 | 1316 | 1385 | 1342 | 1310 | 1351 | 1370 | 1360 | 1297 | 1388 | 1388 |
Collected over 9/20/20 - 3/31/21 -- A period of over six months. Non-serious events are listed at a 0% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| Holdout Control | — | — | — |
| Default Reservations Opt-Out Condition | — | — | — |
| Default Reservations Opt-In Condition | — | — | — |
| Intergroup Competition Treatment Condition | — | — | — |
| Intergroup Competition Control Condition | — | — | — |
| Flu Shot for You Symbolic Condition | — | — | — |
| Flu Shot for You Herd Immunity Condition | — | — | — |
| Flu Shot for You Control Condition | — | — | — |
| Prosocial Condition | — | — | — |
| Self-Oriented Condition | — | — | — |
| Information Vivid Condition | — | — | — |
| Information Basic Condition | — | — | — |
| Information Control Condition | — | — | — |
| Sharing Humor Condition | — | — | — |
| No Humor Condition | — | — | — |
| Healthy Habits Easy Health Behavior Condition | — | — | — |
| Healthy Habits Difficult Health Behavior Condition | — | — | — |
| Healthy Habits Control Condition | — | — | — |
| Just-In-Time Reminders 24-Hour Condition | — | — | — |
| Just-In-Time Reminders 15-Minute Condition | — | — | — |
| Age, Categorical(Participants) | Holdout Control | Default Reservations Opt-Out Condition | Default Reservations Opt-In Condition | Intergroup Competition Treatment Condition | Intergroup Competition Control Condition | Flu Shot for You Symbolic Condition | Flu Shot for You Herd Immunity Condition | Flu Shot for You Control Condition | Prosocial Condition | Self-Oriented Condition | Information Vivid Condition | Information Basic Condition | Information Control Condition | Sharing Humor Condition | No Humor Condition | Healthy Habits Easy Health Behavior Condition | Healthy Habits Difficult Health Behavior Condition | Healthy Habits Control Condition | Just-In-Time Reminders 24-Hour Condition | Just-In-Time Reminders 15-Minute Condition | Total |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| <=18 years | 22 | 24 | 21 | 20 | 31 | 21 | 21 | 15 | 24 | 24 | 22 | 31 | 24 | 14 | 24 | 19 | 16 | 19 | 20 | 28 | 440 |
| Between 18 and 65 years | 2950 | 2920 | 2921 | 2940 | 2942 | 2941 | 2916 | 2923 | 2932 | 2955 | 2902 | 2948 | 2961 | 2950 | 2942 | 2927 | 2956 | 2932 | 2947 | 2959 | 58764 |
| >=65 years | 770 | 793 | 767 | 775 | 785 | 807 | 782 | 794 | 772 | 798 | 748 | 772 | 752 | 750 | 807 | 793 | 804 | 793 | 774 | 771 | 15607 |
| Age, Continuous(years) | Holdout Control | Default Reservations Opt-Out Condition | Default Reservations Opt-In Condition | Intergroup Competition Treatment Condition | Intergroup Competition Control Condition | Flu Shot for You Symbolic Condition | Flu Shot for You Herd Immunity Condition | Flu Shot for You Control Condition | Prosocial Condition | Self-Oriented Condition | Information Vivid Condition | Information Basic Condition | Information Control Condition | Sharing Humor Condition | No Humor Condition | Healthy Habits Easy Health Behavior Condition | Healthy Habits Difficult Health Behavior Condition | Healthy Habits Control Condition | Just-In-Time Reminders 24-Hour Condition | Just-In-Time Reminders 15-Minute Condition | Total |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Mean | 50.3 ± 16.2 | 50.7 ± 16.4 | 50.5 ± 16.3 | 50.7 ± 16.2 | 50.5 ± 16.2 | 50.9 ± 16.3 | 50.5 ± 16.4 | 50.8 ± 16.6 | 50.9 ± 16.2 | 50.6 ± 16.2 | 50.8 ± 16.1 | 50.8 ± 16.1 | 50.7 ± 16.1 | 50.5 ± 16.2 | 50.9 ± 16.3 | 51.0 ± 16.3 | 51.0 ± 16.0 | 50.7 ± 16.3 | 50.7 ± 16.2 | 50.5 ± 16.0 | 50.7 ± 16.2 |
| Sex: Female, Male(Participants) | Holdout Control | Default Reservations Opt-Out Condition | Default Reservations Opt-In Condition | Intergroup Competition Treatment Condition | Intergroup Competition Control Condition | Flu Shot for You Symbolic Condition | Flu Shot for You Herd Immunity Condition | Flu Shot for You Control Condition | Prosocial Condition | Self-Oriented Condition | Information Vivid Condition | Information Basic Condition | Information Control Condition | Sharing Humor Condition | No Humor Condition | Healthy Habits Easy Health Behavior Condition | Healthy Habits Difficult Health Behavior Condition | Healthy Habits Control Condition | Just-In-Time Reminders 24-Hour Condition | Just-In-Time Reminders 15-Minute Condition | Total |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Female | 2056 | 2109 | 2079 | 2067 | 2096 | 2097 | 2018 | 2091 | 2083 | 2120 | 2030 | 2107 | 2060 | 2104 | 2098 | 2085 | 2159 | 2120 | 2101 | 2091 | 41771 |
| Male | 1686 | 1628 | 1630 | 1668 | 1662 | 1672 | 1701 | 1641 | 1645 | 1657 | 1642 | 1644 | 1677 | 1610 | 1675 | 1654 | 1617 | 1624 | 1640 | 1667 | 33040 |
| Race/Ethnicity, Customized(Participants) | Holdout Control | Default Reservations Opt-Out Condition | Default Reservations Opt-In Condition | Intergroup Competition Treatment Condition | Intergroup Competition Control Condition | Flu Shot for You Symbolic Condition | Flu Shot for You Herd Immunity Condition | Flu Shot for You Control Condition | Prosocial Condition | Self-Oriented Condition | Information Vivid Condition | Information Basic Condition | Information Control Condition | Sharing Humor Condition | No Humor Condition | Healthy Habits Easy Health Behavior Condition | Healthy Habits Difficult Health Behavior Condition | Healthy Habits Control Condition | Just-In-Time Reminders 24-Hour Condition | Just-In-Time Reminders 15-Minute Condition | Total |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Race category — Asian | 86 | 82 | 91 | 99 | 86 | 75 | 87 | 88 | 93 | 83 | 90 | 91 | 87 | 88 | 93 | 84 | 80 | 89 | 85 | 77 | 1734 |
| Race category — Black | 751 | 729 | 736 | 688 | 730 | 717 | 711 | 705 | 719 | 755 | 676 | 667 | 713 | 673 | 741 | 676 | 722 | 714 | 698 | 701 | 14222 |
| Race category — Hispanic | 187 | 177 | 173 | 168 | 157 | 180 | 156 | 174 | 174 | 177 | 181 | 143 | 177 | 183 | 154 | 160 | 162 | 175 | 145 | 188 | 3391 |
| Race category — Other | 140 | 114 | 149 | 126 | 134 | 147 | 130 | 116 | 140 | 108 | 139 | 128 | 144 | 131 | 128 | 135 | 113 | 144 | 134 | 138 | 2638 |
| Race category — White | 2578 | 2635 | 2560 | 2654 | 2651 | 2650 | 2635 | 2649 | 2602 | 2654 | 2586 | 2722 | 2616 | 2639 | 2657 | 2684 | 2699 | 2622 | 2679 | 2654 | 52826 |
Documents are hosted by the registry — open the source record to download them.
Plan to share: Yes — Aggregate data and code used for analyses conducted on participants enrolled from September through December is available at https://osf.io/tucjs/?view_only=c491df37a33840abbdedda4e60176f34. This reflects the analyses and data included in this paper: https://www.pnas.org/content/118/20/e2101165118. Researchers interested in using individual-level data to replicate our results should contact the Behavior Change for Good Initiative at the University of Pennsylvania (bcfg@wharton.upenn.edu) and must sign a standard medical data nondisclosure agreement to access the data on a protected medical server.
Supporting information: Study protocol, Sap, Analytic code
This study is completed, as verified in Jan 2022. You cannot join it, but the record below documents what was studied.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
University of Pennsylvania