Text-based Interventions to Promote COVID-19 Vaccinations

This study investigates whether and which type of text-based interventions affect the take-up of the COVID-19 vaccine. The primary research question is whether vaccine takeup can be boosted by a text-message intervention 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. Then patients eligible for the study will be randomized at a 1:4 ratio into a holdout control arm that does not receive a text message vs. a text-message arm that receives a text message.

The secondary research question concerns which type of text message is more effective. To study this question, a nested 2x2 factorial design within the text-message arm will be used, where the two factors will be a) whether patients receive the link to an educational video specifically designed to shift patients' intentions to get the COVID-19 vaccine and b) whether the text message contains language aimed at encouraging patients to follow through on their intentions.

• In the Holdout arm: patients will not receive text messages 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 Simple Text sub-arm, participants will not receive any additional information.

• In the Simple Text+Video sub-arm, together with the appointment link, participants will also receive a link to a 2-minute video in the text message. The video contains information about the prevalence of COVID-19 and the effectiveness and safety of the COVID-19 vaccine.

• In the Enhanced Text sub-arm, in addition to the appointment link, the text message will use enhanced language aimed at reducing psychological barriers that prevent patients from scheduling their appointment.

• In the Enhanced Text+Video sub-arm, in addition to the appointment link, the text message will encourage patients to watch a 2-minute video (the same as in the Simple Text+Video sub-arm) and use enhanced language aimed at reducing patients' psychological barriers of following through on scheduling an appointment.

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 the first batch of patients, those in the text-message arm will receive the text message within 4 -10 days after the initial invitation is sent (because the infrastructure of running this study is not ready until then). For subsequent batches of patients, they will be randomized and receive the text message (if they are not in the holdout arm) the first weekday after the initial communication goes out. 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.