Impact of a large-scale immunization initiative in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC)

CONTEXT Inner-city immunization rates have lagged behind those in other areas of the country. OBJECTIVE To evaluate the impact of an initiative linking immunization with distribution of food vouchers in the inner city. DESIGN Retrospective analysis of immunization data gathered in 1996 and 1997. SETTING Nineteen Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) sites serving 30% of the Chicago, III, birth cohort. PARTICIPANTS A total of 16581 children 24 months old or younger. INTERVENTIONS Voucher incentives (varying frequency of food voucher issuance based on immunization status) and assessment of immunization status and referral to immunization provider. MAIN OUTCOME MEASURES Age-appropriate immunization rates and WIC enrollment rates. RESULTS During the 15-month period of evaluation, immunization rates increased from 56% to 89% at sites performing voucher incentives. The proportion of children needing voucher incentives declined from 51% to 12%. Sites performing assessment and referral, but not providing voucher incentives, showed no evidence of improvement in immunization coverage. No difference was observed in enrollment rates between sites performing voucher incentives and those that did not. CONCLUSION Applied in a large-scale, programmatic fashion, voucher incentives in WIC can rapidly increase and sustain high childhood immunization rates in an inner-city population.