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.

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.

Eligible patients will be randomly assigned to one of four arms: Pennsylvania Lottery Scratch-Off Financial Incentive Certain Cash Payout Financial Incentive Reminder / Active Control Arm (No Financial Incentive) No Treatment Control Arm

Providers who prescribe vaccination and diagnose conditions will not be randomized to study arms or informed of patient assignment. Although patients will not be explicitly informed of which arm they were randomized to, they will be aware of the messages they receive.

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

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.

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.

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)

During the 2021-22 flu season (Up to 11 months, from the time the patient is randomized through July 31, 2022)

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

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.

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.