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The article by Smith et al. in the September/October 2015 issue of Public Health Reports (PHR) used the National Immunization Survey (NIS) to provide information on measles immunization among young children and adolescents with finer detail than previously reported.1 One of the long-term goals of immunization surveillance is to identify local areas of lower rates by geography or demography; in their article, Smith et al. used NIS data to produce measles immunization rates for 210 U.S. counties selected by NIS sample size.
Another approach to identifying pockets of need is to use state immunization registries or immunization information systems (IISs). IISs are population-based repositories of state and local immunization records. I recently described in PHR a methodological foundation for using IIS data to calculate teen populations and immunization rates.2 IISs such as the Oregon ALERT IIS offer the potential for finding county-level or smaller pockets of need. Although there is a need to compare IIS data across states and to validate local IIS estimates, it is important to account for structural and population differences across IISs. Matching IIS data with NIS local estimates is one method by which local estimates can be validated.
Among the 210 U.S. counties for which Smith et al. produced NIS measles immunization estimates, five were in Oregon. For these five Oregon counties, it is possible to compare local (county) estimates between the IIS and NIS using data on measles, mumps, rubella (MMR) vaccine coverage (Table). In this comparison, county IIS rates for two doses of the MMR vaccine were also included for context, because two doses of MMR vaccine are recommended.
The NIS-Teen adolescent rates and the Oregon ALERT IIS rates for ≥1 dose of MMR vaccine are undistinguishable, given 95% confidence intervals. Comparing the two categories produced a Cohen's w of 0.007, indicating that differences are small. This concordance suggests that further work in integrating NIS and IIS surveillance is warranted. In an ideal immunization surveillance system, the NIS could provide a basis for state-to-state comparisons and selected small-area validation against state IIS-determined rates, while local areas could be examined by using state IIS data.