Effectiveness and Cost-Effectiveness of Linking the Special Supplemental Program for Women, Infants, and Children (WIC) and Immunization Activities

Abstract

To raise immunization coverage among children at risk for underimmunization, we evaluated the effectiveness and cost-effectiveness of immunization activities in the Special Supplemental Program for Women, Infants and Children (WIC). A controlled intervention trial was conducted in seven WIC sites in Chicago between October 1990 and March 1994. At intervention sites, staff screened children for vaccination status at every visit, referred vaccine-eligible children to either an on-site WIC nurse, on-site clinic, or off-site community provider, and issued either a 3-month supply of food vouchers to up-to-date children or a 1-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 second birthday; cost-effectiveness was approximated for each of the three referral interventions. After one year, up-to-date vaccination coverage increased 23% above baseline for intervention groups and decreased 9% in the control group. After the second year, up-to-date vaccination further increased to 38% above baseline in intervention groups and did not change in the control group. The total cost per additional up-to-date child ranged from $30 for sites referring children off-site to $73 for sites referring children on-site to a nurse. 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 between WIC and immunization programs by building on WIC's access to at-risk populations is worth the investment.