Improving Coverage Rates and Tackling Disparities: A Canadian Immunization Intervention

Background: In 2001-2005, we found statistically significant geographical disparities in immunization coverage rates for two-year-olds in Saskatoon, Saskatchewan, Canada. For instance, the average complete Measles, Mumps, and Rubella (MMR) immunization coverage rate for two-year-olds in low-income neighbourhoods was 43.7%, compared to 69.1% in the rest of the city. Both of these rates were far below the nationally recommended rate of 95%. A phone survey with parents was conducted in 2006 to determine the causes underlying incomplete immunization, as well as to determine which evidence-based option parents preferred to keep children up-to-date on immunizations. Based on the results of this survey, a telephone/letter reminder system for parents was implemented in 2007.

Objectives: To determine the effectiveness of an evidence-based immunization intervention that was implemented to: a) improve coverage rates overall; and b) to ameliorate geographical disparities in early childhood immunization coverage.

Methods: MMR records for children were extracted from the Saskatchewan Immunization Management System from 2000 until March 2010. Coverage rates were assessed for significant differences before and after the introduction of the intervention using Poisson Regression in SAS 9.2.

Results: We determined that after the introduction of the immunization reminder system, coverage rates for MMR significantly increased across all neighbourhoods by approximately 10%. Geographical disparities decreased only slightly, which led to the introduction of a targeted reminder intervention in 2008. Preliminary results indicate the targeted reminder intervention has served to decrease disparities further.

Conclusions: A simple, relatively inexpensive intervention, with both a targeted and universal component, has been quite successful at raising immunization coverage rates in Saskatoon overall and reducing disparities between neighbourhoods. There is still room for improvement however, since coverage rates are below the national recommended rate, suggesting further intervention is required.