This study will be a multisite, cluster randomized, pragmatic trial to evaluate the effectiveness of personalized nudges to clinicians and patients, relative to a control, to increase flu vaccination rates among older adults in accordance with CDC guidelines. This will include clinician and patient level nudge interventions, with an additional, intensified nudge intervention for patients identified as high risk for not receiving a flu vaccine. Among the intervention clinics, patients will receive pre-visit text message reminders about the flu vaccine, and clinicians will receive a default pended order in the visit encounter in the EHR, along with monthly peer comparison feedback about their flu vaccine completion rate. Patients identified as high risk for noncompletion will be individually randomized to receive an additional bidirectional text message nudge or the standard text messaging.

Many older adults are at risk of illness, hospitalization, and death from vaccine-preventable diseases. More than half of older adults in the United States are not vaccinated for flu which has remained relatively constant over the past decade, and there are racial, ethnic, and socioeconomic disparities in care. In this study, we will evaluate personalized nudges to clinicians and patients to help increase flu vaccination rates during primary care visits among older adults, with a particular focus on population subgroups at high risk for vaccine noncompletion. In a partnership between Penn Medicine and University of Washington (UW) Medicine, this will be a 6-month, multisite, cluster randomized, pragmatic trial with an additional intensification arm for high-risk patients.

Patient Inclusion Criteria:

All patients must meet the following criteria to be eligible:

1. Age >50 years
2. A scheduled new or return (non-urgent/sick) primary care appointment at one of the study practices at the Penn Medicine, UW Medicine, or Lancaster General Hospital
3. Have not received their annual flu vaccine during the active intervention period (September- February)
4. Eligible to receive the flu vaccine

For the high risk intensification nudge, at least one of the following criteria must be met to be considered high risk and randomized to receive the intensification nudge:

1. Age ≥ 70 years
2. Living in a lower income community (lowest quartile, zip-code based)
3. Did not receive a flu vaccine in the previous calendar year
4. Self-identifies as Non-Hispanic Black

Patient Exclusion Criteria:

1. Have a documented allergy to flu vaccine
2. Have a flu vaccine exclusion modifier in Health Maintenance
3. Have opted out of research according to individual site guidelines and policies
4. Have no phone number (home or mobile) listed in their chart

Clinician Inclusion Criteria:

Clinicians must meet the following criteria to be eligible to receive peer comparison feedback:

1. Practicing physician (MD, DO) or advanced practice provider (NP, PA) with the exception of residents and fellows
2. Have a minimum patient panel of at least 50 patients, and
3. Practicing at a clinical site randomized to receive the clinic-level nudge interventions.

We will share our analytical code(s).

Within one year of trial completion

All inquiries related to the code should be directed to the PI.

Baseline characteristics are reported for the Main Study Period only - Clinic Level Randomization (Control and Intervention). Patients in the High Risk arms are accounted for in the Intervention arm as a whole, but were additionally randomized at the Individual Level, as noted in the Participant Flow.

Each patient was monitored for adverse events for 3 months. Adverse events were collected mid-way through the trial at 3 months for all participants enrolled through the end of December 2023 and again at the end of the trial follow up period, 3 months after enrollment ended (May 2024), for all enrolled participants.

Per our DSMB-approved DSMP, severe adverse events will not include death as no reasonable evidence exists to suggest death would result from outreach or communication to encourage standard clinical care for flu vaccination. Therefore, All-Cause Mortality was not assessed. Adverse events are assessed for the Main Study Period arms only - Control (except Messaging, see footnote) and Intervention - as the patients in the High Risk arms are already accounted for in the Intervention arm total.