The Psychological Effects of Interruptions in Covid-19 Vaccine Supply on the Demand for Vaccination: Experimental Evidence from Sierra Leone

Last registered on December 19, 2021
View Trial History

Pre-Trial

Trial Information

General Information

Title
The Psychological Effects of Interruptions in Covid-19 Vaccine Supply on the Demand for Vaccination: Experimental Evidence from Sierra Leone
RCT ID
AEARCTR-0008710
Initial registration date
December 18, 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 19, 2021, 1:43 PM EST

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

Locations

Country
Sierra Leone
Region
Nationwide

Primary Investigator

Name
Anne Karing
Affiliation
University of Chicago
Contact Primary Investigator

Other Primary Investigator(s)

PI Name
Samantha Horn
PI Affiliation
Carnegie Mellon University
Contact Investigator
PI Name
Rachel Glennerster
PI Affiliation
University of Chicago
Contact Investigator
PI Name
Fatu Emilia Conteh
PI Affiliation
Innovations for Poverty Action
Contact Investigator

Additional Trial Information

Status
In development
Start date
2021-12-18
End date
2022-02-01
Keywords
Behavior, Health
Additional Keywords
Psychology and Economics, Behavioral Economics
JEL code(s)
C93, I12, I18, D91
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
COVID-19 vaccine supplies to low-income countries are intermittent and subject to bottlenecks, resulting in occasional vaccine stockouts. It is unknown what the impacts of the supply interruptions are on vaccine demand. Lack of vaccine supply has a clear mechanical effect on vaccination rates - it is impossible to vaccinate without an available vaccine. However, interruptions in supply may also impact demand through other channels. Low availability may heighten vaccine demand by creating a sense of scarcity or lower vaccine demand via motivated thinking as individuals devalue goods that they cannot access (sour grapes effect) or are provided with a ready excuse to not follow through on vaccination if already reluctant (a type of narrative). We use administrative data on individual level vaccination status and quasi-experimental methods (regression discontinuity, difference-in-differences design) to evaluate the impact of exposure to interrupted vaccine supply on vaccine take-up. We complement the observational study with an experiment to investigate underlying behavioral mechanisms. In a first experiment, we exogenously vary the information individuals receive about a recent stockout to test the impact of scarcity on beliefs about vaccine efficacy and demand.
External Link(s)

Registration Citation

Citation
Conteh, Fatu Emilia et al. 2021. "The Psychological Effects of Interruptions in Covid-19 Vaccine Supply on the Demand for Vaccination: Experimental Evidence from Sierra Leone ." AEA RCT Registry. December 19. https://doi.org/10.1257/rct.8710-1.0
Sponsors & Partners
Experimental Details

Interventions

Intervention(s)
We deliver information about a recent stockout of the AstraZeneca vaccine via SMS alongside a reminder for the second dose. The SMS are directly sent through the Sierra Leone Ministry of Health's messaging platform. For a subset of participants we also deliver the same information via a phone call on behalf of the Ministry of Health, implemented by our research partner RamLabs.
Intervention Start Date
2021-12-18
Intervention End Date
2022-02-01

Primary Outcomes

Primary Outcomes (end points)
Completion (0/1) and timeliness of 2nd vaccine dose. This data is available from administrative data collected by the Sierra Leone Ministry of Health.

For the subsample of individuals who we called successfully, outcomes also include i) beliefs about vaccine efficacy, ii) perceived cost of vaccination, iii) demand for the vaccine and iv) beliefs about vaccine availability.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
Individuals are randomized into two arms:
Arm 1: Two SMS reminders about second vaccine dose
Arm 2: Two SMS reminders about second vaccine dose + information about a recent stockout of the AstraZeneca Vaccine

For a subset of participants we also deliver the same information via a phone call. We implement a phone survey following the delivery of the information message.


Experimental Design Details
Randomization Method
Randomization via Stata, stratified by gender and vaccination due date.
Randomization Unit
Individual
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
N/A

Sample size: planned number of observations
Target SMS sample: approx. 10,000 individuals Target call sample: approx. 4,100 individuals The sample sizes are an approximation since they are based off first dose vaccination entries in the Government Covid-19 vaccine registry. The registry is updated with delays, due to data first being entered on paper and later being digitized.
Sample size (or number of clusters) by treatment arms
50/50 split across arms.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials
IRB

Institutional Review Boards (IRBs)

IRB Name
Sierra Leone Ethics and Scientific Review Committee
IRB Approval Date
2021-12-16
IRB Approval Number
N/A
IRB Name
University of Chicago Social and Behavioral Sciences IRB
IRB Approval Date
2021-12-08
IRB Approval Number
IRB21-1513
Analysis Plan

Post-Trial

Post Trial Information

Study Withdrawal

There is information in this trial unavailable to the public. Use the button below to request access.

Request Information

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