sure had occurred and that there were no more development costs. Both analyses place rotavirus vaccine in Level III.
The Level IV candidate vaccines include those whose development might seem less compelling because of limited disease burden, primarily because of low numbers of cases. Several of the candidate vaccines in this category would be used by restricted populations. These populations are limited by geography (e.g., Borrelia burgdorferi, Histoplasma capsulatum, and Coccidioides immitis vaccines) or by occupation or activity. For example, the shigella and enterotoxigenic Escherichia coli vaccines are targeted to overseas travelers, including members of the military.
As stated several times in the report, the committee has not recommended which vaccines should be accorded development priority, nor will it recommend which vaccines should not be developed. Research and development efforts related to Level IV candidate vaccines can be justified in several ways. Research on these vaccines can lead to fundamental discoveries important to other candidate vaccines in the future or to other areas of basic research. Disease patterns could change, increasing the disease burden and making the need for these vaccines more compelling. The discussion of the development of the polio vaccine (Chapter 2) demonstrates that disease epidemiology can indeed change in a relatively short time, making what once seemed like a minor disease a much bigger concern; in this case, ongoing research on poliovirus and poliovirus vaccines contributed greatly to the speedy development of two complementary vaccine strategies once the need was recognized. These Level IV candidate vaccines could also be important due to the burden of disease in other countries, which is not factored into this analysis. The committee argued in Chapter 3 that the inclusion of a candidate vaccine for malaria or for dengue hemorrhagic fever in a report focused on U.S. public health problems was less compelling than inclusion of other candidate vaccines. An analysis of international disease burden would be likely to result in a more favorable cost-effectiveness result for such candidate vaccines.
As this chapter illustrates, a cost-effective analysis is an important tool available to policymakers concerned with vaccine research and development, as well as with vaccine program implementation. Not every scenario could be analyzed and presented, but an important tool has been developed and recommended for use. Prominent candidate vaccines have been used to illustrate the model. The availability of the software and spreadsheets used in the analysis of Vaccine X and of the 26 candidate vaccines means that dialogue around vaccine research and development priorities can continue with a common tool and a common language.