not to vaccinate a child during a sick-child visit.2 Table 1 shows immunization levels observed among children 24 months old in each of CDC's four diagnostic studies and potential levels that the investigators believed could be achieved by eliminating missed opportunities.

Table 1:

Percentage of Actual and Potential Vaccination Coverage Among 24-Month-Old Children by Individual Vaccine Doses and Site, 1991-92a

"Assumes all missed opportunities to vaccinate had been eliminated.

DTP/DT = diphtheria and tetanus toxoids and pertussis vaccine/diphtheria and tetanus toxoids. MMR = measles-mumpsrubella vaccine.

Source: Morbidity and Mortality Weekly Report, 43:39 (October 7, 1994), 711.

2Baltimore investigators found that diagnoses commonly recorded at sick-child visits in which an opportunity to immunize was missed without valid contraindication included gastroenteritis, otitis media, skin infection, and upper respiratory infection.

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The diagnostic studies' findings regarding missed opportunities were consistent across the four studies, even though they used different methodologies. The studies concurred that 2-year-olds missed opportunities very frequently during visits to health care providers: 82 percent of children studied in Rochester missed one or more opportunities, 75 percent in Baltimore, 69 percent in Los Angeles, and 64 percent in Philadelphia. Assuming baseline coverage of 60 percent, these research projects found that eliminating all missed opportunities would alone account for a third to a half of the increase needed to reach the 90-percent goal for 1996. However, as table 1 shows, eliminating missed opportunities alone would not raise immunization rates to the targeted 90percent levels in all cases.

The results of CDC's four diagnostic studies indicate that while no single factor or category of factors accounts for undervaccination, access to health care among underimmunized children is not generally a problem. The diagnostic studies suggest that achieving and sustaining a high coverage level will require a variety of interventions aimed at changing the practices of providers that result in missed opportunities. Specifically, the findings do not provide sufficient evidence to conclude that providing free vaccines through VFC will boost coverage for most under immunized children, for whom vaccines are already free.

In addition to the four CDC studies, we examined other studies and information cited by CDC as addressing the role of vaccine cost in delayed immunization. CDC identified six types of evidence to support the notion that vaccine cost is a barrier:

1.

2.

3.

increases in vaccine cost over the past decade;3

surveys of health care providers inquiring about the frequency with which they had referred patients to public health providers for immunization, their reasons for doing so, and their opinions regarding a universal vaccine purchase program;

reports from health departments of increased
referrals from private providers;

4.

surveys of parents visiting public health clinics
regarding their reasons for using the clinics;

5.

policy studies addressing the relationship between health insurance coverage, health care utilization, and immunization; and

'See our July 21, 1993, correspondence to the Honorable John Dingell and July 27, 1993, correspondence to the Honorable Dale Bumpers, noting problems in linking price changes to low coverage.

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6.

comparisons of immunization rates between states with and without universal vaccine distribution programs.

Unlike the diagnostic studies, which examined populations at high risk of underimmunization to assess the relationship between immunization status and a variety of potential barriers, the additional research cited by CDC tended toward a more narrow investigation of particular factors, such as providers' referral patterns. We found that, for the purpose of assessing the role of vaccine cost in underimmunization, this research suffers from several conceptual and methodological problems, such as failure to distinguish vaccine costs from other fees associated with immunization, inability to determine that the factors actually measured (such as provider referrals to public health clinics) were valid indicators of eventual failure to receive immunization, and reliance on opinion data collected in surveys rather than through analysis of the immunization status of representative samples of children. For example, CDC officials acknowledged that providers' fees in the private sector would be about $40 per office visit and about $15 per dose, representing potentially about 60 percent of the total cost of full immunization, but much of the evidence they cited failed to distinguish between the cost of vaccine, which is addressed by VFC, and these fees, which are not. Comparisons of immunization rates between states operating universal distribution programs and other states do not permit accounting for the various other factors that may affect rates in these states.4

To summarize, the studies we examined and the other sources of information available to us lacked sufficient evidence to conclude that the major factor addressed by VFC, vaccine cost, has been a significant barrier to immunization. It appears that efforts to address a variety of other barriers may be equally or more important in improving immunization levels. We have discussed our findings and conclusions with responsible CDC officials. They are in general agreement with our finding that there is not sufficient evidence to conclude that vaccine cost is among the most significant barriers to immunization.

Mr. Chairman, this concludes my remarks. I would be happy to answer any questions that you or members of the Committee may have.

"U.S. General Accounting Office, Childhood Immunization: Opportunities to Improve Immunization Rates at Lower Cost, GAO/HRD-93-41 (Washington, D.C.: March 1993).

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