Lottery Incentive Nudges to Increase Influenza Vaccinations

In the current study, the study team will explore whether small incentives are effective at promoting flu vaccine uptake. The study is designed to compare the relative efficacy of incentives of equal perceived expected value (EV) or equal implementation costs, to assess whether people are more likely to get vaccinated in response to lotteries with very high payoffs than to small certain cash payout or slightly higher-probability, more moderate payoffs. In particular, given the potential appeal of official state lottery tickets, one study arm will receive a Pennsylvania scratch-off lottery ticket for getting a flu vaccine. A primary hypothesis is that lotteries will outperform simple reminders (encouraging respondents to get the flu shot at their upcoming appointment) and the standard of care, representing the ambient healthcare system and public health campaigns to increase vaccination.

Study Overview

• Status: Completed
• Conditions: Influenza; Health Promotion; Health Behavior; Vaccination
• Intervention / Treatment: Behavioral: Reminder; Behavioral: Financial incentive; Behavioral: Lottery

Detailed Description

During the 2021-22 flu season, the study team will contact Geisinger patients who have a primary care or specialist appointment scheduled during flu season and encourage them to get a flu shot.

Patients will be randomized into 4 to 9 study arms, depending on a sample size projection completed in August 2021. Arms will test the relative efficacy of a variety of small monetary incentives on flu shot uptake. Incentives may include (a) a $1 Pennsylvania scratch-off lottery ticket (with top prize of $5,000), (b) $1 in cash, (c) entry into a raffle for $5,000 absent upfront odds, (d) entry into a raffle for $5,000, with 1-in-5,000 odds of winning, (d) entry into a raffle for $50, with 1-in-50 odds of winning, and (e) entry into a raffle for $500, with 1-in-500 odds of winning. There will be one no-contact control arm and at least 1 reminder control arm (with additional control arms added given sufficient sample size and additional message versions to be tested).

Included in the study will be current Geisinger patients 18+ years of age with no contraindications for flu vaccine who have an appointment scheduled during the study period with a provider who can administer the vaccine. The primary study outcomes will be the rates of flu vaccination and flu diagnosis during the 2021-22 season by targeted patients.

• Study Type: Interventional
• Enrollment (Actual): 57581
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Pennsylvania
    • Danville, Pennsylvania, United States, 17822
      • Geisinger Clinic

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Aged 18+
• Pennsylvania mailing address listed
• Geisinger primary care provider (PCP) assigned
• Upcoming appointment with PCP or select specialist who stocks and can administer the vaccine during the study period

Exclusion Criteria:

• Has opted out of receiving messages from Geisinger on all modalities being tested

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Pennsylvania (PA) Lottery Scratch-Off Financial Incentive; Participants in this arm will receive a message stating that they will receive a PA lottery $1 scratch-off ticket if they get a flu shot at an upcoming appointment. The message will mention that they could win $5,000 (the top prize for the scratch-off game). Note: $1 scratch-off products vary over time; at study implementation, an active game with top prize of $5,000 (or the next-highest top prize) will be selected and will define the prize in the raffle absent upfront odds	Behavioral: Reminder; Letter, short message service (SMS) text, phone, and/or email; Behavioral: Financial incentive; Letter, SMS, phone, and/or email; Behavioral: Lottery; Letter, SMS, phone, and/or email
Experimental: Certain Cash Payout Financial Incentive; Participants in this arm will receive a message stating that they will receive $1 in cash if they get a flu shot at an upcoming appointment.	Behavioral: Reminder; Letter, short message service (SMS) text, phone, and/or email; Behavioral: Financial incentive; Letter, SMS, phone, and/or email
Experimental: Reminder / Active Control (No Financial Incentive); Participants in this arm will receive a message stating that they can get a flu shot at an upcoming appointment. These participants will not be offered a financial incentive for getting a flu shot.	Behavioral: Reminder; Letter, short message service (SMS) text, phone, and/or email
No Intervention: No Treatment Control; No additional contact beyond standard Geisinger flu shot communications

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Flu Vaccination at Appointment	Received flu vaccination at relevant PCP or specialty appointment.	3 days after patient is randomized

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Flu Vaccination Within 7 Days	Received flu vaccination	Within 7 days of when patient is randomized
Flu Diagnosis	Received a "high confidence flu" diagnosis (with positive polymerase chain reaction [PCR]/antigen/molecular test) and/or "likely flu" diagnosis (as assessed via International Classification of Disease [ICD] codes or Tamiflu administration or positive PCR/antigen/molecular test) Note that "likely flu" is a superset of the "high confidence flu" diagnoses.	During the 2021-22 flu season (Up to 8 months, from the time the patient is randomized through April 30, 2022)
Flu Complications	Diagnosed with flu-related complications	During the 2021-22 flu season (Up to 11 months, from the time the patient is randomized through July 31, 2022)

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Flu Vaccination (Among Subject Cohabitants) Within 28 Days	Cohabitant of study subject received flu vaccination	Within 28 days of when the study subject is randomized
Flu Vaccination at Appointment by Gender	Received flu vaccination at relevant PCP or specialty appointment.	3 days after the patient is randomized.
Flu Vaccination at Appointment by Race	Received flu vaccination at relevant PCP or specialty appointment.	3 days after the patient is randomized.
Flu Vaccination at Appointment by Ethnicity	Received flu vaccination at relevant PCP or specialty appointment.	3 days after the patient is randomized.

Collaborators and Investigators

• Sponsor: National Bureau of Economic Research, Inc.
• Collaborators: National Institute on Aging (NIA); Massachusetts Institute of Technology; Geisinger Clinic
• Investigators: Principal Investigator: Michelle N Meyer, PhD JD, Geisinger Clinic; Principal Investigator: Christopher F Chabris, PhD, Geisinger Clinic

Study record dates

Study Major Dates

• Study Start (Actual): September 4, 2021
• Primary Completion (Actual): December 31, 2021
• Study Completion (Actual): December 31, 2022

Study Registration Dates

• First Submitted: August 4, 2021
• First Submitted That Met QC Criteria: August 11, 2021
• First Posted (Actual): August 19, 2021

Study Record Updates

• Last Update Posted (Actual): March 25, 2025
• Last Update Submitted That Met QC Criteria: December 13, 2024
• Last Verified: December 1, 2024

More Information

Terms related to this study

• Keywords: Financial Incentives; Lottery
• Additional Relevant MeSH Terms: Respiratory Tract Infections; Infections; Orthomyxoviridae Infections; RNA Virus Infections; Virus Diseases; Respiratory Tract Diseases; Influenza, Human
• Other Study ID Numbers: 2021-0484; P30AG034532 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Data with no personally identifiable information will be made available to other researchers on the Open Science Framework for transparency. This will include the essential data and code needed to replicate the analysis that yielded reported findings.
• IPD Sharing Time Frame: By the paper's online publication date or within 12 months of the primary completion date (whichever comes first). Data will remain available for as long as the Open Science Framework hosts it.
• IPD Sharing Access Criteria: The data on the Open Science Framework will be open to anyone requesting that information.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ANALYTIC_CODE

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No