The way ahead for vaccines and vaccination: symposium summary.

In this summary, several biological and non-biological constraints to rapid progress in the molecular vaccine era are highlighted such as genetically-based unresponsiveness, induction of inappropriate immune responses, sustaining protective immunity in the vaccines problems in demonstrating efficacy, and ensuring availability and usage of this class of biologicals throughout the world. Some approaches to increasing immunogenicity are discussed with emphasis on composite antigens. Finally, the eight broad strategies for constructing vaccines outlined by Chanock in 1984 are re-examined.