Experimental Design Details
We aim to recruit 10,000 adult subjects from the Contra Costa Health Plan (CCHP) via a 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 California's Immunization Registry (CAIR) and the EMR.
Because of administrative delays that led to a large pause in recruitment, we will analyze the data both overall and separately across recruitment waves.