The estimate for the cost of development includes all future costs needed to bring the vaccine to licensure, irrespective of the funding source. Factors considered in estimating this amount were the current state of vaccine development, the complexity of the problem (e.g., difficulties encountered in culturing the pathogen), the availability of animal models, the number of alternatives to be tested in human clinical trials, and possible difficulties in conducting clinical trials or in establishing efficacy and safety in the target population.

The time to licensure is defined as the shortest time in which a vaccine could be licensed, if all developmental stages are completed without major delays. Factors considered in determining this time were similar to those for estimating the cost of development.

The committee also considered interrelationships among the probability of success, the cost of development, and the time to licensure; for example, the extent to which extra funding could significantly reduce the time to licensure for a particular vaccine.

The committee based its predictions on the characteristics of individual vaccines primarily on known characteristics of existing vaccines of similar type, for example, live attenuated virus, polysaccharide, or subunit vaccine. These predictions also incorporate assumptions about likely licensure requirements.

The prediction of a vaccine’s efficacy represents a population-based measure of protection rather than a measure of antibody production in an individual and is given by

Factors considered in estimating the efficacy were the type of pathogen and number of serotypes involved in the disease, the nature of the vaccine candidate, and the extent of immunity from natural infection.

Vaccine efficacy predictions also incorporate the assumption that vaccines will be administered at ages compatible with delivery through EPI (see Appendixes D-1 through D-19 for specific details). unfortunately, the EPI delivery schedule may not be ideal for some