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Heard immunity: effective messaging for a future COVID-19 vaccine
Last registered on July 10, 2020

Pre-Trial

Trial Information
General Information
Title
Heard immunity: effective messaging for a future COVID-19 vaccine
RCT ID
AEARCTR-0006133
Initial registration date
July 09, 2020
Last updated
July 10, 2020 10:01 AM EDT
Location(s)

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Primary Investigator
Affiliation
Sol Price School of Public Policy/USC
Other Primary Investigator(s)
Additional Trial Information
Status
In development
Start date
2020-07-13
End date
2020-09-14
Secondary IDs
Abstract
This study uses a survey experiment to determine the most effective messaging to persuade people to take up a future vaccine for COVID-19. Ending the pandemic necessitates enough vaccination to achieve herd immunity, but survey evidence suggest up to 50% of people are hesitant to vaccinate. The survey divides respondents into one control and four treatment groups. Each treatment group is exposed to a message emphasizing either the benefits of vaccination or the risks of avoiding vaccination, to the respondent personally or to society in general. The survey is administered by USC's Understanding America Survey to a nationally representative panel. The outcome measure of interest is differences in self-reported intention to vaccinate for the four treatment arms relative to control, using a means-comparison test with inference adjusted for the testing of four hypotheses.
External Link(s)
Registration Citation
Citation
Duquette, Nicolas. 2020. "Heard immunity: effective messaging for a future COVID-19 vaccine." AEA RCT Registry. July 10. https://doi.org/10.1257/rct.6133-1.0.
Experimental Details
Interventions
Intervention(s)
Intervention Start Date
2020-07-13
Intervention End Date
2020-09-14
Primary Outcomes
Primary Outcomes (end points)
Self-reported intention to vaccinate against COVID-19 in the future
Primary Outcomes (explanation)
Respondents are asked whether they want the coronavirus vaccine when it becomes available. I code "Yes" as 1 and "No" or "I don't know / Not sure" as 0.
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
Survey experiment.
Experimental Design Details
Not available
Randomization Method
By computer
Randomization Unit
Individual
Was the treatment clustered?
No
Experiment Characteristics
Sample size: planned number of clusters
n/a
Sample size: planned number of observations
2200
Sample size (or number of clusters) by treatment arms
440
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
effect size 30% standard deviation is rejected 80% of the time.
IRB
INSTITUTIONAL REVIEW BOARDS (IRBs)
IRB Name
University of Southern California Institutional Review Board
IRB Approval Date
2020-06-10
IRB Approval Number
UP-14-00148-AM080
Analysis Plan

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