Effects of the VFC on Physician Referral for Vaccination

Richard Kent Zimmerman, M.D., M.P.H. - Principal Investigator

Tammy A. Mieczkowski, Ph.D. - Statistician
Mahlon Raymund, Ph.D. - Sample management and CATI programming

Among the barriers to vaccination that the National Vaccine Advisory Committee (NVAC) noted in its report on the 1989-1991 measles epidemic, were the high costs faced by private physicians in purchasing vaccines, inadequate insurance coverage, and referral of children by private physicians to public clinics, thereby fragmenting care. Many surveys of providers reveal that uninsured and, to a lesser degree, Medicaid insured and underinsured children have been referred to public vaccine clinics. In response to these problems, the Vaccines for Children Program was formed to provide free vaccines to providers for uninsured, Medicaid-insured, Native American, and, at federally qualifying health centers, underinsured children.

The effect of the VFC program by itself is somewhat difficult to document for several reasons. First, states have implemented it at various times and in various ways. Second,the VFC was a programmatic intervention without randomizabon; thus, ecologic data on VFC results might be subject to problems from confounding or the ecologic fallacy. Third, other interventions known to raise immunization rates have been implemented in the same time period, making it difficult to determine the effect of any single intervention. Fourth, the childhood vaccination schedule is front-loaded with most doses occurring in the first six months of life; therefore, vaccination rates before and after-VFC cannot readily be determined for individual children.

In 1990-1991 and 1993, before the introduction of VFC, we conducted surveys of 411 Minnesota and 268 Pennsylvania primary care physicians. The survey instrumentwas basically the same for both surveys and included questions about vaccine economics and referral of patients to public clinics. We propose to survey the same physicians again, with the primary issues being any changes in economic barriers over time and the causes for these changes. As secondary issues we will compare physicians' responses on contraindications and health beliefs. This cohort study with pre and post-VFC comparisons of physician responses would not suffer problems arising from the ecologic fallacy and temporality. The survey findings will be validated by review of 35 immunization records for each of 50 physicians selected for this portion of the study. A final activity will be a review of published literature on physician perception of economic barriers to vaccination to determine the feasibility of a meta-analysis.