Figure. CONSORT Flow Diagram.

Patients were eligible for study participation if they were at least 6 months of age at the start of intervention (ie, eligible for influenza vaccination), a primary care patient within the UCLA Health System according to the health system’s criteria, and an active patient portal user (≥1 log-in during the past 12 months), other than initial account log-in. Patients were ineligible if they were not a primary care patient within the UCLA Health System or not an active patient portal user.