Effectiveness and cost-effectiveness of linking the special supplemental program for women, infants, and children (WIC) and immunization activities

Objective: To raise immunization coverage among children at risk for underi mmunization, we evaluated the effectiveness and cost-effectiveness of immun ization activities in the Special Supplemental Program for Women, Infants a nd Children (WIC). Method: A controlled intervention trial was conducted in seven WIC sites in Chicago between October 1990 and March 1994 At intervention sites, staff s creened children for vaccination status at every visit, referred vaccine-el igible children to either an on-site WIC nurse, on-site clinic, or off-site community provider, and issued either a g-month supply of food vouchers to up-to-date children or a I-month supply to children not up-to-date-a usual practice for high-risk WIC children. Our primary measure of effectiveness was the change in the baseline percentage of up-to-date children at the sec ond birthday; cost-effectiveness was approximated for each of the three ref erral interventions. Results: After one year, up-to-date vaccination coverage increased 23% abov e baseline for intervention groups and decreased 9% in the control group. A fter the second year, up-to-date vaccination further increased to 38% above baseline in intervention groups and did not change in the control group. T he total cost per additional up-to-date child ranged from $30 for sites ref erring children off-site to $73 for sites referring children on-site to a n urse. Conclusion: This controlled intervention trial of screening, referral, and a voucher incentive in the WIC program demonstrated a substantial increase in immunization coverage at a low cost. Continuing to design linkages betwe en WIC and immunization programs by building on WIC's access to at-risk pop ulations is worth the investment.