The VFC program had been in place for 16 years as of 2009. The program was designed to provide access to vaccines for financially vulnerable children, and our results suggest that this goal has been achieved for many childhood vaccines.
Approximately half (49.7% ±1.4%) of all children in the U.S. who were aged 19–35 months in 2009 were entitled to VFC vaccines. Our results showed that most VFC-entitled children were on Medicaid, and a high percentage of those children were administered doses from a vaccination provider who was enrolled in the VFC program. All other VFC-entitled children who were on Medicaid but did not receive doses from a provider who was enrolled in the VFC program would have been administered vaccines at no cost through Medicaid's Early and Periodic Screening, Diagnosis, and Treatment program.16
Also, most of the non-Medicaid VFC-entitled children were uninsured, and a high percentage of those children were administered vaccines by a provider enrolled in the VFC program. Thus, a high percentage of the VFC program's entitled population of financially vulnerable children has received VFC vaccines.
However, we found that approximately 9.3% of all children aged 19–35 months were covered by private insurance that did not cover all of the costs of vaccines, and that among those, only 3.4% took advantage of their entitlement to VFC vaccine and were administered doses at an FQHC or RHC. If more of these children were vaccinated at FQHCs or RHCs, it could boost vaccination rates further.
A child's medical home may be either a private or public practice, such as a health department clinic. Our results showed that approximately half of VFC-entitled children received all of their vaccinations at private providers, and nearly one-fifth received all of their vaccinations at public providers. This result suggests that a large percentage of VFC-entitled children receive their primary care from a provider that serves as the child's medical home. Vaccination coverage among VFC-entitled children who use a medical home consistently has been shown to be essentially equivalent to that of privately insured children who are not VFC-entitled.17
For polio, MMR, Hib, Hep B, and VAR, national estimates of vaccination coverage for VFC-entitled children were within approximately three percentage points of those for non-VFC-entitled children. Thus, gaps in vaccination coverage between VFC-entitled and non-VFC-entitled children are narrow and provide evidence that the VFC program's goal of increasing vaccination coverage by eliminating vaccine cost as a barrier to being vaccinated has succeeded for those vaccines. It is not possible to determine what coverage would be without the VFC program. In 1993, when the Childhood Immunization Initiative was created, only diphtheria-tetanus/diphtheria-tetanus-pertussis (DT/DTP), poliovirus, MMR, Hib, and Hep B vaccines were recommended by the Advisory Committee on Immunization Practices (ACIP).18
In 1992, estimated vaccination coverage for all children aged 19–35 months was 59% (±2.9%) for ≥4 doses of DT/DTP, 72.4% (±2.3%) for ≥4 doses of poliovirus, 82.5% (±3.8%) for ≥1 dose of measles-containing vaccine, and 28.2% (±2.7%) for ≥3 doses of Hib; CDC surveillance of vaccination coverage for Hep B had not commenced.19
In 2009, estimated vaccination coverage for these vaccines among non-VFC-entitled children was 87.1% (±1.2%) for DTaP, 94.2% (±0.8%) for polio, 91.5% (±0.9%) for MMR, 85.2% (±1.2%) for Hib, and 92.9% (±0.9%) for Hep B. For children who were VFC-entitled, estimated coverage rates were 81.0% (±1.7%) for DTaP, 91.7% (±1.2%) for polio, 88.8% (±1.4%) for MMR, 82.3% (±1.6%) for Hib, and 92.2% (±1.1%) for Hep B. Among children aged 19–35 months in 2009 who were not VFC-entitled, the HP 2010 vaccination coverage objectives of 90% were not achieved nationally for two out of five of those vaccines. Among 19- to 35-month-old children who were VFC-entitled, the objectives were not achieved for three out of five of the vaccines. It should be noted, however, that for Hib, a recent vaccine shortage may explain the failure to achieve the 90% coverage objective.20
Despite not achieving the 90% coverage objectives for many of these vaccines, the higher coverage rates for both VFC-entitled and non-VFC-entitled children show the great strides that have been made in the last two decades. Further diligence is required so that HP 2020 vaccination coverage goals are achieved for all recommended vaccines.
The findings in this article are subject to at least four limitations. First, NIS is a landline telephone survey and does not have data from children who live in households with no telephone service or only cellular phone service. Therefore, our estimates could be biased insofar as households that are not covered by the NIS are different from those covered by the NIS with respect to vaccination coverage. However, recent work suggests that bias in surveys that only sample households with landline telephones may be small.21,22
Second, underestimates of vaccination coverage might have resulted from the exclusive use of provider-reported vaccination histories, because completeness of these records is unknown. Third, in our research, VFC status was measured at the time of the NIS telephone interview. Insofar as some children may have been eligible before that interview, but not at the time of the telephone interview, the percentage of children who had ever been entitled to VFC vaccines may be underestimated. Fourth, ascertainment of provider enrollment in the VFC program from the mail survey to age-eligible children's providers could be imperfect. Mis-measurement of provider enrollment in the VFC program could lead to the underestimation of the percentage of children served by VFC, particularly if clinic staff who provide data on that measurement are not familiar with their state's VFC program.