COVID-19 Booster Incentives in a County-Run Health System

Last registered on May 11, 2023
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Pre-Trial

Trial Information

General Information

Title
COVID-19 Booster Incentives in a County-Run Health System
RCT ID
AEARCTR-0010610
Initial registration date
December 08, 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
December 13, 2022, 11:18 PM EST

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

Last updated
May 11, 2023, 1:17 PM EDT

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

Locations

Country
United States of America
Region
CA

Primary Investigator

Name
Mireille Jacobson
Affiliation
USC
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Other Primary Investigator(s)

PI Name
Tom Chang
PI Affiliation
Contact Investigator
PI Name
Manisha Shah
PI Affiliation
Contact Investigator

Additional Trial Information

Status
Completed
Start date
2022-12-08
End date
2022-12-23
Keywords
Health
Additional Keywords
JEL code(s)
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
The goal of this work is to understand whether small financial incentives and messaging can increase the take-up of COVID-19 boosters among patients empaneled at a county public health system. The motivation for this work is the relatively low take-up of COVID-19 boosters. In California, where our experiment is based, only 59% of the population has been boosted, with only 13% receiving the recommended bivalent booster (State of California, 2022).
External Link(s)

Registration Citation

Citation
Chang, Tom, Mireille Jacobson and Manisha Shah. 2023. "COVID-19 Booster Incentives in a County-Run Health System." AEA RCT Registry. May 11. https://doi.org/10.1257/rct.10610-1.1
Sponsors & Partners

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Experimental Details

Interventions

Intervention(s)
Intervention Start Date
2022-12-08
Intervention End Date
2022-12-23

Primary Outcomes

Primary Outcomes (end points)
Vaccine booster take-up at 2 weeks
Primary Outcomes (explanation)
Indicator for booster vaccination within 2-weeks

Secondary Outcomes

Secondary Outcomes (end points)
We will also study treatment effects by race, gender, age, insurance type, message modality (SMS or email) and timing of first COVID-19 vaccine.
Secondary Outcomes (explanation)
We want to understand potential heterogenous responses.

Experimental Design

Experimental Design
This study will involve messages with and without incentives as well as a pure control arm (no message) to individuals who are not update on the COVID-19 booster.
Experimental Design Details
There will be three arms. A message arm encouraging COVID-19 booster vaccination, a message arm encouraging COVID-19 booster vaccination and offering a $25 amazon gift card to those who receive a booster within 2 weeks of the message, and a control or “treatment as usual” arm that receives no message. The study sample includes all adult patients impaneled at Contra Costa Regional Medical Center (CCRMC) who meet the following conditions:

1. Age: 18 and above
2. Vaccination status: at least one COVID-19 vaccination (primary series or monovalent booster) but no vaccination dose within the past 2-months, per current CDC bivalent booster recommendations
3. Active phone number or email
4. Do not have “Do not contact” flag

The number of patients who meet this requirement is expected to be approximately 60,000.

Randomization will be stratified by message type (SMS or email)
Randomization Method
Randomization will be done in office by computer.
Randomization Unit
Individual
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
57,000 individuals
Sample size: planned number of observations
57,000 individuals
Sample size (or number of clusters) by treatment arms
19,000 individuals per arm
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
See analysis plan
Supporting Documents and Materials

Documents

Document Name
Messages
Document Type
other
Document Description
File
Messages

MD5: 04653f11ed88fc5ac3a1e77a7cda77b1

SHA1: 6e0ebbca976612b1191701eff47ac698e95a78bd

Uploaded At: December 08, 2022

IRB

Institutional Review Boards (IRBs)

IRB Name
Insitutional Review Committee - Contra Costa Health Services
IRB Approval Date
2022-11-21
IRB Approval Number
N/A
IRB Name
University of Southern California
IRB Approval Date
2022-02-24
IRB Approval Number
UP-21-01097
Analysis Plan

Analysis Plan Documents

Analysis Plan

MD5: 94d63b84a02b158ffbc092b8191947f1

SHA1: 0e65d45b9c2dbe533fedf933c85b697faef61f64

Uploaded At: December 08, 2022

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