The effectiveness of assessment and referral on immunization coverage in the special supplemental nutrition program for women, infants, and children.

Background: The use of immunization assessment and referral (A/R) in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) has been shown to produce dramatic improvements in vaccination coverage when coupled with parental incentive; however, data are lacking to support the use of A/R alone.

Objective: To determine the effectiveness of A/R in increasing immunization coverage among WIC participants.

Design: Participating WIC centers were assigned to1 of 3 interventions that delivered A/R of varying frequency or a control group.

Setting: Twenty of the largest Public Health Foundation Enterprises-WIC centers in Los Angeles County.

Participants: Children continuously enrolled in participating WIC centers from 6 to 24 months of age.

Intervention: Assessment of child's vaccination status followed by referral to a health care provider for those lacking indicated vaccinations.

Main Outcome Measure: Up-to-date (UTD) status at 24 months of age for all recommended vaccines.

Results: Baseline coverage rates were similar among all study sites (overall, 77% UTD). After the study period, compared with the controls (88% UTD), we found no differences in immunization coverage among WIC centers that administered A/R at every visit (every 2 months) to all children (90% UTD; adjusted odds ratio [OR], 1.02; 95% confidence interval [CI], 0.54-1.94), every 6 months to all children (89% UTD; OR, 0.98; 95% CI, 0.62-1.56), or every visit to children found to be behind at 8 months of age (89% UTD; OR, 0.89; 95% CI, 0.48-1.68).

Conclusion: In this urban population of WIC children with high baseline immunization coverage, A/R was not effective in increasing immunization coverage.