The Effect of the State Children’s Health Insurance Program on Immunization Rates: Evidence from the National Immunization Survey

Grant Description: The researchers studied the effect of the State Children’s Health Insurance Program (SCHIP) on children’s immunization rates. Specifically, they assessed the likelihood that low-income children, after the implementation of SCHIP, are up to date on vaccinations, receive their immunizations on time, and receive vaccinations from a provider that offers comprehensive pediatric services (instead of a vaccine-only public health setting). The researchers compared immunization coverage rates and the sites where the vaccines were received before SCHIP was implemented with those after implementation in all 50 states. The results for low-income children were compared to a control group of non-low-income households. The objective of the project was to evaluate the effectiveness of SCHIP in accomplishing the specific objective of increasing immunization among low-income children.

Policy Summary: By age two a child who is up to date for immunizations will have received up to 19 shots delivered over eight visits at a market cost of $525 dollars for the vaccines alone, a far more expensive and demanding regimen than the 8 shots received in 1987. In recognition of the potential importance of health insurance to immunization coverage rates, the State Children’s Health Insurance Program (SCHIP) mandated that all plans cover the cost and administration of childhood vaccines. We use data from the recently released National Immunization Survey for the years 1995 to 2002 to address two questions: First, is SCHIP associated with differential gains in age-appropriate immunization rates among poor and near-poor children relative to their non-poor counterparts? And second, is the uptake of new vaccines among poor and near-poor children faster than would have been observed in the absence of SCHIP? We show that the probability that a poor or near-poor child is up to date for the 4:3:1:3:3 vaccine series increased approximately 10 percentage points before and after SCHIP. However, we observed a similar increase for non-poor children. As to new vaccines, we demonstrate that uptake of the varicella vaccine increased between 8 and 19 percentage points more among poor and near-poor relative to non-poor children after implementation of SCHIP. However, we present evidence that the differential gains by poor and near-poor children are more likely related to the diffusion of new vaccines and not specifically SCHIP. Our results suggest that the availability of publicly provided health insurance for poor and near-poor children may be a necessary but not a sufficient condition to narrow the income gradient for immunizations. The infrastructure of vaccine delivery such as the availability of public clinics, outreach campaigns, as well as mandatory vaccination for pre-school may be more important than health insurance coverage.