Through a large, population-level quality improvement effort within the Children's Hospital of Philadelphia Care Network, we will evaluate text message reminders on flu vaccination rates for both patients with and without a scheduled well child care visit during flu season.

This is a randomized control trial with two patient cohorts: patients with and without a scheduled well child care visit during the upcoming 2024 flu season. Patients with a scheduled well child visit will be randomized into one of three groups (control, intervention message #1, or intervention message #2). Patients within the intervention groups will receive a one-time text message reminder to get their flu shot for their child at their child's upcoming well visit. Intervention groups will be texted at the same time, the same month as their child's well visit. The text message language will differ between groups. Patients without a scheduled upcoming well child visit during the 2024 flu season will also be randomized into one of three groups (control, intervention message #1, or intervention message #2). Intervention groups will be texted at the same time, at the start of flu season. The text message language will differ between groups.

Flu vaccine uptake will be measured within each patient cohort.

Inclusion Criteria:

• All patients between ages 6 months-18 years old who have an upcoming well visit during the Fall of 2024 (September through December 2024) or had a completed well visit from January 2023 through August 2024
• Patients have a mobile phone number within their medical record
• Patients have opted-in to text communications from CHOP
• English-speaking

Exclusion Criteria:

• Subjects who do not meet the above inclusion criteria will be excluded

Patients (recipients of text message reminders) will not know which group they are in.