Despite clinicians’ best efforts, the USA’s national immunization coverage of 76% is far below the 90% target set in the Healthy People 2000 report. Students of public health policy have identified three problem areas as the main causes of this poor performance: 1) low socio-economic conditions, 2) parents and providers who tend to over estimate their children’s immunization status, and 3) missed opportunities to bring patients’ immunizations up to date at routine or sick patient visits.

Researchers in Rochester, NY, undertook an 18-month, randomized, controlled clinical trial of two interventions that were designed to improve immunization rates within the community. They randomly assigned 3015 infants to 1 of 4 study groups: 1) tracking/outreach with provider prompting, 2) tracking/outreach only, 3) provider prompting only, and 4) control. Over 90% of all subjects completed the study and were available for follow-up data analysis.

At the beginning of the study the average immunization coverage was 82% and there were no differences among the groups. At the end of the study the tracking/outreach with provider prompting and tracking/outreach only groups both had 95% immunization coverage, while the provider prompting alone had 76% coverage and the control group 74% coverage. An analysis of variance showed that tracking with outreach increased immunization coverage by 20 percentage points (p<0.001) and decreased immunization delay by 63 days (p<0.001). The prompting intervention alone had no measurable effect. The cost associated with the tracking and outreach was $95/child over the 18 month period.