Testing SMS interventions to increase COVID-19 vaccination completion in Kenya

Last registered on August 22, 2023

Pre-Trial

Trial Information

General Information

Title
Testing SMS interventions to increase COVID-19 vaccination completion in Kenya
RCT ID
AEARCTR-0009930
Initial registration date
August 15, 2022

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
August 18, 2022, 3:22 PM EDT

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

Last updated
August 22, 2023, 11:26 AM EDT

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

Locations

Region

Primary Investigator

Affiliation
University of Michigan

Other Primary Investigator(s)

PI Affiliation
The University of Michigan
PI Affiliation
The University of Chicago
PI Affiliation
The University of Chicago

Additional Trial Information

Status
Completed
Start date
2022-07-22
End date
2023-02-15
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
This study tests SMS messages designed to increase completion rates among people who received a first but not second dose of the COVID-19 vaccine. Partnering with the Kisumu County Department of Health, four experiments were conducted to test a series of SMS- based interventions aimed at encouraging participants who had already been vaccinated for COVID-19 once to complete their vaccination regimen. The first experiment focuses on messages related to different reasons to get vaccinated. The subsequent experiments tests different deadlines to get the vaccine and obtain an airtime benefit for doing so.
External Link(s)

Registration Citation

Citation
Carney, Kevin et al. 2023. "Testing SMS interventions to increase COVID-19 vaccination completion in Kenya." AEA RCT Registry. August 22. https://doi.org/10.1257/rct.9930-2.0
Experimental Details

Interventions

Intervention(s)
Experiment 1 Messages: Framing the Benefits of Getting Vaccinated
1. Control: No message
2. Reminder: Reminder from Kisumu MOH to finish your COVID-19 vaccination.
3. Reminder + info: Reminder from Kisumu MOH to finish your COVID-19 vaccination. Reply 1 (no cost) for more info.
4. Reserved for you: Reminder from Kisumu MOH to finish your COVID-19 vaccination. Your 2nd jab has been reserved for you. Reply 1 (no cost) for more info.
5. COVID side effects: Reminder from Kisumu MOH to finish your COVID-19 vaccination. Mild side effects are normal & mean you are building protection. Reply 1 (no cost) for more info.
6. Duty: Reminder from Kisumu MOH to finish your COVID-19 vaccination. It’s our duty to protect each other. Vaccination is part of that. Reply 1 (no cost) for more info.
7. COVID still a threat: Reminder from Kisumu MOH to finish your COVID-19 vaccination. COVID-19 is still out there. Get your 2nd jab today! Reply 1 (no cost) for more info.
8. Time-limited reimbursement - deadline of one week: Reminder from Kisumu MOH to finish your COVID-19 vaccination. Get your 2nd jab in the next week and receive 100/= airtime! Reply 1 (no cost) for more info.

Experiment 2 Messages: Optimizing the Timing of Vaccination Benefits
1. Control: No message
2. Reminder: Reminder from Kisumu MOH to finish your COVID-19 vaccination.
3. Reminder + info: Reminder from Kisumu MOH to finish your COVID-19 vaccination. Reply 1 (no cost) for more info.
4. Time-limited reimbursement - deadline of current day: Reminder from Kisumu MOH to finish your COVID-19 vaccination. Get your 2nd jab today and receive 100/= airtime! Reply 1 (no cost) for more info.
5. Time-limited reimbursement - deadline of one week: Reminder from Kisumu MOH to finish your COVID-19 vaccination. Get your 2nd jab in the next week and receive 100/= airtime! Reply 1 (no cost) for more info.
6. No limit reimbursement (with reimbursement valid for one month): Reminder from Kisumu MOH to finish your COVID-19 vaccination. Get your 2nd jab and receive 100/= airtime! Reply 1 (no cost) for more info.
7. Scarcity: Reminder from Kisumu MOH to finish your COVID-19 vaccination. Hurry! The next 100 to get a 2nd jab receive 100/= airtime. Reply 1 (no cost) for more info.

Experiment 3 and 4 Messages: Optimizing the Timing of Vaccination Benefits
1. Control: No message
2. Reminder: Reminder from Kisumu MOH to finish your COVID-19 vaccination.
3. Reminder + info: Reminder from Kisumu MOH to finish your COVID-19 vaccination. Reply 1 (no cost) for more info.
4. Time-limited reimbursement - deadline of current day: Reminder from Kisumu MOH to finish your COVID-19 vaccination. Get your 2nd jab today and receive 100/= airtime! Reply 1 (no cost) for more info.
5. Time-limited reimbursement - deadline of one week: Reminder from Kisumu MOH to finish your COVID-19 vaccination. Get your 2nd jab in the next week and receive 100/= airtime! Reply 1 (no cost) for more info.

Upon replying 1, respondents receive an SMS stating: Your 2nd vaccine dose reduces your risk of getting COVID-19 & severe illness. Available for free at most health facilities. Full facilities list: [tracked link to facilities]

Where airtime is offered, upon replying 1, respondents will also receive an SMS stating: 100/= airtime will be sent to your phone if you reply here with the facility name and date where you got your 2nd jab. Offer not transferable.
Intervention (Hidden)
Intervention Start Date
2022-07-22
Intervention End Date
2023-01-30

Primary Outcomes

Primary Outcomes (end points)
Rates of completion of the full, two-dose vaccination course. Vaccination completion rates will be measured at several points in time using administrative data from the Kisumu County Department of Health. The primary outcome will be the rate of full (two-dose) vaccination. The speed of second-dose completion will also be analyzed.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
To supplement the administrative vaccination records, the SMS system will also collect data on people’s engagement with (responses to) the intervention messages.

The first outcome to analyze is the rate at which participants reply “1” in each of the conditions where they are invited to do so. The second outcome is the rate at which participants click the link they are provided upon replying “1,” measured using an individualized link for each treatment condition. The final outcome is the response rate in the airtime conditions when people are asked to reply with their vaccination date and location.
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
This study involves the 29,474 people in three subcounties of Kisumu County who had received a first, but not second, dose of the COVID-19 vaccine as of July 17, 2022. The subcounties included in the study are Kisumu Central, Kisumu West, and Nyakach. These particular subcounties were chosen to exclude locations where the Kisumu County Department of Health already had other COVID-19 experiments ongoing in partnership with our research team.

The two experiments described above were scheduled to occur approximately one week apart. Half of the individuals were randomized to the first experiment, and half to the second. Within each experiment, individuals were randomized in equal proportions into the eight treatment conditions listed above (seven messages and one control group). Each individual within a trial received the message assigned to them at the same time, and received any relevant follow-up messages immediately upon replying “1”. This is the extent of the interventions.
Experimental Design Details
Randomization Method
Randomization occurred at the individual level and was stratified on observables in the vaccination database: gender, age (using an indicator for being above age 35), and subcounty where the first vaccination dose occurred. The randomization process occurred in an office on a 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
26,755
Sample size (or number of clusters) by treatment arms
Experiment 1
1. Control: 1,834
2. Baseline reminder: 1,842
3. Baseline reminder + info: 1,846
4. Reserved for you: 1,842
5. Covid side effects: 1,842
6. Duty: 1,843
7. Covid is still a threat: 1,841
8. Airtime (1 week deadline): 1,846

Experiment 2
1. Control: 1,710
2. Baseline reminder: 1,716
3. Baseline reminder + info: 1,719
4. Time-limited reimbursement - deadline of current day: 1,716
5. Time-limited reimbursement - deadline of one week: 1,719
6. No limit reimbursement (with reimbursement valid for one month): 1,716
7. Scarcity: 1,726
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
In experiment 1, the study is able to detect a difference in vaccination rates of at least 3.45 percentage points between any two treatments, assuming a 15% vaccination rate in the control group. In experiment 2, the study is able to detect a difference in vaccination rates of at least 3.58 percentage points between any two treatments, assuming a 15% vaccination rate in the control group.
IRB

Institutional Review Boards (IRBs)

IRB Name
The University of Chicago Social and Behavioral Sciences Institutional Review Board
IRB Approval Date
2022-02-10
IRB Approval Number
IRB22-0020

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