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COVID-19 Vaccination Take-Up in a County-Run Medicaid Managed Care Population

Last registered on May 05, 2021

Pre-Trial

Trial Information

General Information

Title
COVID-19 Vaccination Take-Up in a County-Run Medicaid Managed Care Population
RCT ID
AEARCTR-0007405
Initial registration date
March 25, 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
March 26, 2021, 10:49 AM EDT

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

Last updated
May 05, 2021, 2:03 PM EDT

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

Locations

Primary Investigator

Affiliation
USC

Other Primary Investigator(s)

PI Affiliation
USC
PI Affiliation
UCLA

Additional Trial Information

Status
In development
Start date
2021-05-15
End date
2022-05-15
Secondary IDs
Abstract
In this work, we are partnering with Contra Costa Health Services (CCHS), the department of health in Contra Costa County, CA, to measure COVID-19 vaccinations and other COVID-19 related preventive health behaviors in the county’s Medicaid managed care population. Our work will test ways to increase COVID-19 vaccine uptake. We hypothesize that small financial incentives and other low-cost behavioral nudges can be used to increase vaccine uptake and reduce disparities in uptake among diverse racial/ethnic minority populations.
External Link(s)

Registration Citation

Citation
chang, Tom, Mireille Jacobson and Manisha Shah. 2021. "COVID-19 Vaccination Take-Up in a County-Run Medicaid Managed Care Population." AEA RCT Registry. May 05. https://doi.org/10.1257/rct.7405-2.0
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Experimental Details

Interventions

Intervention(s)
We will test the impact of financial incentives, the highlighting of a convenient scheduling link, messaging from race and gender concordant vs. discordant providers and message type on COVID-19 vaccine uptake.
Intervention Start Date
2021-05-15
Intervention End Date
2021-08-15

Primary Outcomes

Primary Outcomes (end points)
Vaccine uptake at 1-month
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Vaccine take-up at 6-months and at other intervals

For the subset of people who are part of the survey panel, we will also see if there is a change in preventive health behaviors and labor supply (assume follow-up surveys).

From administrative data, we will also study health care utilization and COVID-19 testing.

We will also study heterogeneous treatment effects by race, gender and age.
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
We will test the impact of financial incentives, messages from race and gender concordant vs. discordant providers, as well as message type on COVID-19 vaccine uptake.
Experimental Design Details
Approximately 10,000 adult subjects will be recruited from the Contra Costa Health Plan (CCHP) via baseline survey. Subjects who complete the baseline survey will be randomized to the following arms:
1. Control Arm (n=2,500)
2. Informational Arm: state/treatment as usual message vs. safety and effectiveness information vs. information on consequences of going unvaccinated, race and/or gender concordant or discordant [7,500]

Each of these arms will be interacted with a financial incentive of $10 (N=2,500) or $50 (N=2,500) and, separately with a convenient link to the county public vaccine appointment scheduling system highlighted for participants (N=5,000).

The above treatments are designed to test the role of the following on vaccine take-up:

• Financial incentives [N=5,000] vs. no financial incentives [N=5,000]
o 2,500 will be randomized to a $10 incentive and 2,500 to a $50 incentive
• Convenient scheduling link highlighted [N=5,000] vs. not [N=5,000]
• Messaging [N=7,500] vs not [2,500]
o Message type: treatment as usual [N=2,500] vs. safety and effectiveness [N=2,500] vs. consequences of not vaccinating [N=2,500]
• Race concordant [N=2,500] vs. race discordant messenger [N=2,500]
• Gender concordant [N=2,500] vs. gender discordant messenger [N=2,500]

We will obtain survey data on preventative health behaviors, including mask-wearing, hand washing, and willingness to vaccinate. We will obtain data on vaccine take-up from the EMR and California's Immunization Registry (CAIR).
Randomization Method
computer
Randomization Unit
members of Contra Costa Health Plan
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
10,000 unvaccinated members of Contra Costa Health Plan
Sample size: planned number of observations
10,000
Sample size (or number of clusters) by treatment arms
We will randomize the 10,000 respondents to one of four arms:

1. Control arm [2,500]
2. Messaging/Information Arm 1: no information/emotional message [N=2,500]
3. Messaging/Information Arm 2: provider safety and effectiveness information [N=2,500]
4. Messaging/Information Arm 3: information on consequences of going unvaccinated [N=2,500].

Each of these four arms will be interacted with a financial incentive of $10 (N=2,500) or $50 (N=2,500) and, separately with a convenient link to the county public vaccine appointment scheduling system highlighted for participants (N=5,000). Provider messages will also be randomized by race and gender concordance.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
We power our study for our primary outcome, vaccine take-up. For the purposes of this power calculation, we assume that among the vaccine hesitant only 10% of the population will get vaccinated in the absence if our interventions. In unadjusted comparisons, we will be able to detect a change in vaccinations of 1.68 percentage points (16.8% off the mean) for our financial incentive (5,000) vs. control (5,000) or scheduling link vs. control. For any message (7,500) vs. no message (N=2,500) we can detect take-up changes of 1.94 percentage points (19.4% off the mean). For our 3-message type or race or gender concordance (N=2,500 each) comparisons we can detect take-up changes of 2.38 percentage points (23.8% off the mean). Accounting for statistical controls as well as our randomization strata and assuming these increase the R-squared on take-up to 0.25, the MDEs decline to 0.146 percentage points for financial incentives/scheduling link, 1.68 percentage points for any message and 2.1 percentage points for message type or race or gender concordance comparisons. To benchmark these comparisons, we note that Alsan et al. (2019) finds increases in flu shot take-up among African American men, a vaccine hesitant group, of about 22 percentage points for a $5 or $10 incentive. A key difference with our study is Alsan et al. (2019) provided vaccinations on site. Nonetheless, our study will be well-powered if our interventions have impacts even 1/10th the size as those in Alsan et al. (2019). Alsan M., Owen G. and Graziani G. 2019. "Does Diversity Matter for Health? Experimental Evidence from Oakland." American Economic Review 109(12): 4071-4111. DOI: 10.1257/aer.20181446.
IRB

Institutional Review Boards (IRBs)

IRB Name
University of Southern California Institutional Review Board
IRB Approval Date
2021-03-10
IRB Approval Number
UP-21-00030
Analysis Plan

Analysis Plan Documents

Pre-analysis plan

MD5: 232a646b118b6646dd65db7386a35687

SHA1: 5c1350c8a6d1fbb7cb83d06f2cb93cfcec00af10

Uploaded At: May 05, 2021

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