The objective of any vaccine development program is to reduce morbidity, mortality, and costs resulting from disease. Unfortunately, time and resource limitations make it impossible to pursue intensive development programs for all vaccines simultaneously. Priorities must be set in a manner that is consistent both with the needs of the population and the capabilities of current technologies. The committee sought a methodology that would allow quantitative comparison of the burdens of morbidity and mortality resulting from disease candidates for accelerated vaccine development.

In the proposed system, information on morbidity and mortality are combined into a single numerical score for each disease.* The same principles have been used to calculate the expected health benefits from individual vaccine candidates in Chapter 7. Application of the system to diseases that are candidates for long-term rather than accelerated development is discussed in Appendix B.

The methods used to calculate and compare the costs associated with the diseases are described in the latter portion of this chapter, and the cost savings that may be achieved from the vaccines are presented in Chapter 7.

The system described below was designed not only to incorporate information relating to a disease (i.e., incidence, severity, complications, sequelae, duration, and distribution), but also to allow expression of individual value judgments on the undesirability (disutility) of different consequences resulting from that disease. Such value judgments are an inevitable part of the ranking process, whether they are explicit or implicit. The committee chose to make them explicit.