Despite U.S. guidelines for influenza vaccination of all children starting at age 6 months, only about half of children are vaccinated annually leading to substantial influenza disease in children and spread of disease to adults. A major barrier is that families are not reminded about the need for their children to receive influenza vaccination. The investigators will evaluate the impact of patient reminder/recall (R/R) performed by state immunization information systems to improve influenza vaccination rates by using three clinical trials in two states. The investigators will assess effectiveness and cost-effectiveness of phone reminder/recall on improving influenza vaccination rates. The investigators will disseminate the state immunization information system based reminder/recall system to all states for use for both seasonal and pandemic influenza vaccinations with the goal of lowering influenza morbidity.

Annual epidemics of seasonal influenza cause substantial morbidity and mortality in the U.S. with high rates of hospitalizations, emergency department and outpatient visits, and medical costs. Children experience significant morbidity from influenza, and also play a critical role in spreading infection to adults. Since 2010, the Advisory Committee on Immunization Practices (ACIP) has recommended influenza vaccination for all children >6 months of age. However, vaccination rates remain very low-- only 56% of children 2-17 years are vaccinated. Low rates are a concern for both seasonal influenza and in preparation for pandemic influenza. One of the nationally recommended strategies for raising childhood influenza vaccination rates is to use parent reminder/recall (R/R) by phone or mail, which can raise rates by up to 20 percentage points. However, less than 16% of primary care practices use R/R despite many studies showing its effectiveness.

Statewide immunization information systems (IISs) now exist in all states to track childhood vaccinations, but they have not been used for R/R for influenza vaccine because of the lack of evidence for its effectiveness and lack of a template for IIS-based R/R. The investigators have united two leading immunization research groups (Denver, CO and Rochester, NY) to assess the impact of centralized IIS-based influenza vaccine R/R, and to evaluate the effect of intensity of recall (1 v. 2 v. 3 reminders) over usual care. The investigators will also develop tools to aid other states in creating efficient IIS R/R systems for seasonal and possible pandemic influenza outbreaks.

This study has four aims.

Aim 1 is to develop the protocols, clinical decision support, and message content for state IISs to conduct reminder/recall for influenza vaccinations.

Aim 2 is to conduct a pragmatic trial, with randomization at the level of the patient within practices randomly selected to be proportionate to each state, to compare: 1) effectiveness and cost-effectiveness of centralized R/R of different intensity (1 vs. 2 vs. 3 messages) and usual care (0 messages) and 2) effectiveness and cost-effectiveness of R/R in specified subgroups (family medicine vs pediatric provider, rural vs urban, age of child) on receipt of influenza vaccination.

Aim 3 will measure the effect of adding mailed or text message R/R for autodialer failures vs. autodialer-alone R/R on influenza vaccination rates using a 2-arm Randomized Controlled Trial (RCT).

Aim 4 (dissemination aim) will develop a toolkit for state IIS-based influenza vaccine R/R for seasonal and pandemic influenza, and work with key stakeholders on a sustainability plan.

By the end of the study the investigators will have a feasible and cost-effective model to raise child seasonal or possibly pandemic influenza vaccination rates to prevent influenza. The investigators will disseminate the IIS model to all states.

Inclusion Criteria:

• A record in the Colorado Immunization Information System,
• In need of at least one influenza vaccination at time of study,
• Affiliated with a participating practice, or
• Randomly selected among unaffiliated patients.

Exclusion Criteria:

• Opted out of participating in CIIS, or
• Are up-to-date on influenza vaccine