The impact of incentives for vaccination on future vaccination behavior, attitudes, and morals

Last registered on February 28, 2022

Pre-Trial

Trial Information

General Information

Title
The impact of incentives for vaccination on future vaccination behavior, attitudes, and morals
RCT ID
AEARCTR-0008727
Initial registration date
December 20, 2021

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published
December 23, 2021, 9:50 AM EST

First published corresponds to when the trial was first made public on the Registry after being reviewed.

Last updated
February 28, 2022, 7:20 AM EST

Last updated is the most recent time when changes to the trial's registration were published.

Locations

Region

Primary Investigator

Affiliation
University of Zurich

Other Primary Investigator(s)

PI Affiliation
University of Lausanne
PI Affiliation
University of Copenhagen
PI Affiliation
Columbia University
PI Affiliation
University of Chicago
PI Affiliation
Lund University

Additional Trial Information

Status
In development
Start date
2021-12-21
End date
2023-02-27
Secondary IDs
Prior work
This trial is based on or builds upon one or more prior RCTs.
Abstract
We study the long-term impacts of offering monetary incentives for vaccination on future vaccination uptake, safety perceptions, and morals. To do so, we exploit the setting of an earlier study that offered payment to people for getting a first dose of a COVID-19 vaccine (Campos-Mercade et al., 2021), which provides us with random variation in exposure to monetary incentives. We match the data with Swedish registry data on vaccination uptake for the unincentivized second dose. We then survey study participants about their willingness to take a third dose of the COVID-19 vaccine (booster shot), moral values related to vaccination and risk and benefit perceptions of vaccinations.
External Link(s)

Registration Citation

Citation
Campos-Mercade, Pol et al. 2022. "The impact of incentives for vaccination on future vaccination behavior, attitudes, and morals." AEA RCT Registry. February 28. https://doi.org/10.1257/rct.8727-1.1
Experimental Details

Interventions

Intervention(s)
Intervention Start Date
2021-12-21
Intervention End Date
2022-01-31

Primary Outcomes

Primary Outcomes (end points)
1) Uptake second dose (main administrative data outcome measure): Did the participant get the unincentivized second dose of a COVID-19 vaccine?

2) Uptake booster shot: Are you planning to take a third dose of COVID-19 vaccine (booster shot) when it becomes available to you? (Yes/No)

3) Perceived safety and efficacy: Average answer to the following 3 items (Scales: 5-point Likert scale):
- In general, COVID-19 vaccines are safe
- I am worried about the side effects from COVID-19 vaccines (reverse coded)
- COVID-19 vaccines are highly effective at protecting my health

4) Moral values and norms: Average answer to the following 3 items (Scales: 5-point Likert scale):
- I am willing to take the personal costs of getting a COVID-19 vaccine (e.g., time, discomfort, mild side effects) for the greater good of society
- I think people have a civic duty or a moral obligation to get a COVID-19 vaccine
- In general it is seen as odd and not socially appropriate to not take the COVID-19 vaccine
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
See preregistration Plan
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
To address our research questions, we focus on the participants in the Incentives, Control and the No reminders conditions of Campos-Mercade et al. (2021). The Control condition and the No reminders condition did not include any interventions to increase vaccination uptake. In the Incentives condition, participants were offered a monetary incentive of SEK 200 (about US$24) if they got vaccinated within 30 days of the vaccine becoming available to them. First, we examine whether these individuals did or did not get a second dose of a COVID-19 vaccine using data from Swedish administrative registers. Second, we conduct a survey with the participants.
Experimental Design Details
Randomization Method
Randomization in Mercade et al. (2021) was done by a computer
Randomization Unit
Randomization in Mercade et al. (2021) was at the individual level.
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
The surveys are collected through an online survey with the help of the Swedish survey company Norstat. We aim at recruiting as many participants in the Incentives, Control and No reminders conditions of Campos-Mercade et al. (2021) as possible. We expect around 3000 participants to participate in the survey.
Sample size: planned number of observations
We expect around 3000 participants to participate in the survey.
Sample size (or number of clusters) by treatment arms
We expect around 3000 participants to participate in the survey.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
We expect that we will have around 700 observations in the Incentives condition and 2300 observations in the Control and No reminders conditions. This would give us 80% power to detect an effect size (= Cohen’s d) of about 0.12 for our outcome measures, meaning that we could detect small effects.
IRB

Institutional Review Boards (IRBs)

IRB Name
IRB Approval Date
IRB Approval Number
Analysis Plan

Analysis Plan Documents

Preanalysis Plan

MD5: 3cc705cd7de27932c35a3e4ac6146d68

SHA1: bf2e20be6accc92e95c2e6117f70e6126a2f2a69

Uploaded At: December 20, 2021

Post-Trial

Post Trial Information

Study Withdrawal

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Intervention

Is the intervention completed?
No
Data Collection Complete
Data Publication

Data Publication

Is public data available?
No

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials