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 two types of R/R (autodial v. 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.