Learning Objectives for this Presentation:
By the end of the presentation participants will be able to:
1. Visualize immunization pockets of need on an electronic map.
2. Understand how a Geographic Information System (GIS) displays data from an immunization registry.
3. Appreciate the potential research and programmatic solutions available from a GIS linked to a robust immunization registry.

Background:
The national coverage rate for the 4:3:1:3:3 immunization series exceeds 80%. However coverage remains varied at the state and local level, with some jurisdictions reporting rates below 70%. Identifying areas of low immunization coverage has traditionally involved time-consuming and costly surveys, demographic proxies or retrospective analyses.

Objectives:
GIS technology has emerged as a tool to manage and display immunization data, but a lack of large electronic immunization datasets has limited its use. Electronic immunization registries may bridge this data gap. By linking a GIS model to registry data representing more than 90% of an actual population, we sought to develop and demonstrate a rapid and accessible tool for identifying local pockets of need.

Methods:
We used the Oregon ALERT registry to collect records for 2602 patients aged 18-35 months receiving immunizations from providers in one county. These data were assigned geographic coordinates based on the patient's home address and mapped using GIS software. A one square mile grid was developed to identify neighborhoods where immunization coverage for the 4:3:1:3:3 series was above or below the county average (66%).

Results:
In an 870 square mile area, 24 square miles were identified as potential pockets of need.

Conclusions:
The tool generates a detailed, yet anonymous, image of immunization needs when linked to a registry containing records for more than 90% of the children residing in the target area. Compared to larger-area geographic analyses (e.g., using Census tracts), this tool allows users to target interventions more effectively.