ObjectiveImmunization data are vital to support responses to vaccine-preventable disease outbreaks. The Oregon Immunization Program developed a unique prototype instrument—the Rapid Response Tool (RRT)—that provides population data to local responders within 2 hours of a request. Data outputs include vaccination coverage by age group and zip code; percentages of students with nonmedical exemptions to vaccination requirements, by school; and current, comprehensive lists of local vaccination providers.MethodsThe RRT was demonstrated to staff at 7 Oregon counties and feedback was solicited via comments and a structured survey.ResultsThe RRT received strong support. Attendees identified several uses for RRT data, including outbreak response and ongoing intervention efforts, and they pointed to areas for further development.ConclusionsThe success of the RRT demonstrations illustrates that a well-populated immunization information system can contribute to preparedness work well beyond current standards. (Disaster Med Public Health Preparedness. 2019;13:682–685)