Text-based Reminders to Promote COVID-19 Vaccinations

Our primary research question is whether vaccine takeup can be boosted by a text-message reminder encouraging eligible patients to schedule a vaccination appointment. Patients, when becoming eligible for receiving the COVID-19 vaccine at UCLA Health, will be first notified about their eligibility and encouraged to schedule a vaccination appointment via one of the channels (email, voice call, or snail mail) depending on the contact information available to UCLA Health. Eligible patients will also receive a text-message reminder after the initial invitation. Eight days after the first text reminder, patients eligible for our study will be randomized at a 1:6 ratio into a holdout control arm that does not receive a second text message vs. a text-message arm that receives a second text message.

Our secondary research question concerns which type of text reminder is more effective. To study this question, we will nest a 2x3 factorial design within the text-message arm. The first factor has two levels and is whether the text message focuses on patients' personal benefits or prosocial benefits. The second factor has three levels and is whether the text message highlights the early access patients have to the vaccine, whether it highlights that the vaccine offers the promise of a fresh start, or neither.

• In the Holdout arm: patients will not receive a second text message about COVID-vaccine.

• In the text-message arm, all participants will receive a text message that invites them to schedule their vaccination appointment and includes a link to the appointment website

• In the Self-benefit sub-arm, participants will be reminded that the vaccine helps protect themselves from COVID.

• In the Prosocial-benefit sub-arm, participants will be reminded that the vaccine helps protect their family, friends, and community from COVID.

• In the Early access + self-benefit sub-arm, participants will be reminded that they have early access to COVID-19 vaccine and should take the opportunity to protect themselves from COVID.

• In the Early access + prosocial-benefit sub-arm, participants will be reminded that they have early access to COVID-19 vaccine and should take the opportunity to protect their family, friends, community from COVID.

• In the Fresh start + self-benefit sub-arm, participants will be reminded that the vaccine offers the promise of a fresh start and they should take the opportunity to protect themselves from COVID and chart a new path forward.

• In the Early access + prosocial-benefit sub-arm, participants will be reminded that the vaccine offers the promise of a fresh start and they should take the opportunity to protect their family, friends, community from COVID and help our nation chart a new path forward.

Patients will enter our study on a rolling basis, as they become eligible to get the vaccine (and if they fit our inclusion criteria for receiving the second text message). Those in the text-message arm will receive the second text message on the workday on or closest to the 8th day following the first text message. Specifically, if t denotes the date of the first text message, then t+8 is the 8th day following the first text message.If t+8 is Saturday, the second text message will be sent on Friday; if t+8 is Sunday, the second text message will be sent on Monday. We will measure a) whether patients schedule a COVID-19 vaccination appointment for the first dose and b) whether and when patients get the first dose of COVID-19 vaccine.