• This study will assess the effect of promotional messaging and incentives encouraging influenza vaccination in the Sendero IdealCare policy holders during the 2018-2019 Flu Season. The intervention will consist of influenza vaccination promotion/reminders from Sendero Health Plans to subscribers, including text messages, emails, and tailored direct mail outs, i.e. postcard or a personalized letter, and incentive. The study population consists of approximately 22,500 subscribers enrolled in Sendero IdealCare Plan. The intervention will last approximately four months. The primary endpoints, assessed through administrative claims data, will be getting a flu shot during the 2018-2019 season. Data collected through this study will be used to determine effective components of influenza vaccination promotion campaigns used by a health insurance plan.

Inclusion Criteria:

• Enrollment in Sendero IdealCare health plan as of August 1, 2018
• Age 18 years or older

Exclusion Criteria:

• A coverage termination date listed prior to December 31, 2018.
• Sendero member records lack both a phone number and email address.