This study is related to a previous study, Clinicaltrials.gov ID: NCT02924467. There are some modifications in relation to the intervention arms as well as the use of a different cohort, thereby justifying the second submission to Clinicaltrials.gov. This trial is taking place in New York State, through partnership with the New York State Health Department (excluding New York City), and Colorado. Each state will have it's own Clinicaltrial.gov submission -- this was decided as some of the intervention components are different enough that separate registrations were warranted.

Despite U.S. guidelines for influenza vaccination of all children starting at 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 4 clinical trials (2 per state) in two different states. The investigators will assess effectiveness and cost-effectiveness of 1) autodialer R/R 2) text messages R/R 3) mailed postcard R/R as compared to 4) standard of care control (no R/R).

Annual epidemics of influenza A and B cause substantial morbidity and mortality in the US with high rates of hospitalizations, emergency department visits, outpatient visits, and medical costs. Epidemics cause up to 40,000 deaths/year (mostly elderly) and extensive morbidity among children who play a key role in instigating and expanding epidemics. In addition, concerns about pandemic influenza heighten the importance of new mechanisms to rapidly inform the population about influenza and direct efforts for rapid vaccine delivery.

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. For the 2012-2013 season, only 56% of children 2-17years were vaccinated. Modeling studies suggest that as many as 19 million cases of influenza could be prevented if child vaccination rates were raised to 70% nationally.

The most effective strategy recommended by CDC and the Task Force on Community Preventive Services for improving childhood influenza vaccination rates is reminder/recall (R/R), sent by phone or mail, notifying parents of the need to vaccinate their child. We and others have shown that R/R can improve influenza vaccination rates by up to 20%. However, <16% of practices use R/R; barriers are practice costs, insufficient staff time and expertise, and lack of predictability regarding receipt of vaccine supplies.

Statewide immunization information systems (IISs) now exist in all states to track childhood vaccinations, but they have not been used for influenza vaccine R/R because of lack of evidence for their effectiveness and a lack of a template for IIS-based R/R. The investigators have united two leading immunization research groups (Denver, CO and Rochester (lead by personnel at UCLA), NY) to assess the impact of centralized IIS-based influenza vaccine R/R and to evaluate the effect of three types of R/R (autodialer, text message and mail R/R) 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.

For this second R/R trial in New York State, the intent is to evaluate the impact of reminder recalls, in the form of 1) autodialers 2) text messages and 3) postcards versus the standard of care control group, specifically in relation to raising influenza vaccination rates among children 6m-17 years of age.

The proposed design of this 4-arm RCT:

1. standard of care control
2. autodialer R/R -- with brief educational messages, practice name and practice phone number
3. text message R/R-- with brief educational messages, practice name and practice phone number
4. mailed (postcards) R/R-- with brief educational messages, practice name and practice phone number

Hypothesis 1: All IIS-C R/R modalities will be more effective than usual care

Hypothesis 2: Text messaging will be more cost-effective than other modalities

Inclusion Criteria:

• a record in the New York State Immunization Information System
• in need of at least one influenza vaccination at the time of the beginning of the study
• affiliated with a participating practice (145 randomly selected)

Exclusion Criteria:

• no record within the New York State Immunization Information System
• up to date on their influenza vaccination
• not affiliated with an eligible practice

Aggregate results will be prepared for publication at the end of the trial.