Understanding and overcoming vaccine hesitancy in Latin America: A descriptive and experimental study

Last registered on January 25, 2021

Pre-Trial

Trial Information

General Information

Title
Understanding and overcoming vaccine hesitancy in Latin America: A descriptive and experimental study
RCT ID
AEARCTR-0007080
Initial registration date
January 22, 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
January 25, 2021, 10:09 AM EST

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

Locations

Region
Region
Region
Region
Region
Region

Primary Investigator

Affiliation
Columbia University

Other Primary Investigator(s)

PI Affiliation
Columbia University
PI Affiliation
Columbia University
PI Affiliation
Columbia University
PI Affiliation
Columbia University
PI Affiliation
Columbia University

Additional Trial Information

Status
On going
Start date
2021-01-11
End date
2021-01-29
Secondary IDs
Abstract
COVID-19 has had wide-reaching health and economic consequences across Latin America. Governments throughout the region have begun to distribute approved vaccines to combat its spread. However, absent willingness by citizens to receive these vaccines, vaccination efforts could be seriously hampered. This study first aims to provide descriptive characteristics of vaccine hesitancy in the region. Among the hesitant, we then seek to understand how levels of hesitancy are affected by information relating to health, social, political, and vaccine-specific factors. We thereby aim to identify how governments can frame vaccination campaigns to maximize vaccine uptake. Using an online survey of thousands of respondents across six Latin American countries---Argentina, Brazil, Chile, Colombia, Mexico, and Peru---we randomize (i) the type of public health information that respondents receive about COVID-19 and (ii) different motivations for getting vaccinated, as well as conduct a conjoint experiment to identify the different features of hypothetical, but plausible, vaccine distribution scenarios that may influence vaccine uptake. The findings will inform the scope and contours of vaccine hesitancy in the context of COVID-19 and the efficacy of vaccination campaign strategies.
External Link(s)

Registration Citation

Citation
Argote, Pablo et al. 2021. "Understanding and overcoming vaccine hesitancy in Latin America: A descriptive and experimental study." AEA RCT Registry. January 25. https://doi.org/10.1257/rct.7080
Experimental Details

Interventions

Intervention(s)
This study seeks to understand and remedy the informational, social, and political bases of COVID-19 vaccine hesitancy. To do so, we experimentally test differences in the effects of public health and motivational information interventions. As part of a survey, we randomly assign respondents to receive one of the following types of public health information:
---control
---basic health information (what vaccines do, approval of COVID-19 vaccines, safety and efficaciousness of vaccines)
---basic health information + herd immunity (the share of the population needs to be vaccinated to achieve herd immunity, which is randomly varied between 60, 70, 80%)
---basic health information + herd immunity + current willingness (the share of the population that is currently willing to be vaccinated)
---basic health information + Biden (information explaining that US President Biden recently got vaccinated).

We then cross-randomize this public health information with the following motivational treatments:
---control
---motivation priming the altruistic benefits of getting vaccinated
---motivation priming the social status associated with getting vaccinated
---motivation priming the importance of vaccination for economic recovery

In addition to the informational treatments just described, we further conduct a conjoint experiment that randomly varies features of hypothetical vaccine scenarios.
Intervention Start Date
2021-01-11
Intervention End Date
2021-01-29

Primary Outcomes

Primary Outcomes (end points)
We study three main types of outcome: general willingness to take a COVID-19 vaccine; immediacy of willingness to take a COVID-19 vaccine once available; and a behavioral measure of willingness to receive more information about COVID-19 vaccines.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
We will study a variety of potential mechanisms that could be activated by the different informational treatments, including posterior beliefs about others' willingness to vaccinate, concerns about vaccination, prospects for economic recovery, etc.
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
The treatments are randomized within Qualtrics, blocked at the country x baseline hesitancy x age group level. The information is received around halfway through the experiment, and outcomes are measured after treatment.
Experimental Design Details
Randomization Method
Block randomization within Qualtrics.
Randomization Unit
Information treatments will be randomized at the individual level.
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
Around 6,000 hesitant individual will complete the survey, with around 1,000 from each country.
Sample size: planned number of observations
For most outcomes, we will observe outcomes for all 6,000 individuals. For the conjoint experiments, we will observe 5 outcomes per individual, for a total of around 30,000 outcomes.
Sample size (or number of clusters) by treatment arms
Among the health information treatments: 3/14 control; 3/14 basic health information; 3/14 basic + herd immunity information; 3/14 basic + herd immunity + current willingness information; 2/14 basic + Biden information. Among the cross-randomized motivational information: 1/4 control; 1/4 altruism; 1/4 economic recovery; 1/4 social status.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB

Institutional Review Boards (IRBs)

IRB Name
Columbia Medical School Institutional Review Board
IRB Approval Date
2020-12-22
IRB Approval Number
IRB-AAAT5273
Analysis Plan

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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