ABSTRACT
T he past two decades have witnessed an explosion in the number o f technological and immunological approaches for making new vaccines. These developments have flowed from advances in a broad range o f scientific fields. Some o f the earliest applications o f the newer technologies were to improving previously existing vaccines. However, most recent applications have been directed toward the development o f new vaccines for diseases not previously approachable. The protective immunity elicited by a vaccine ideally would be life long and robust after one or a few doses with minimal side effects (reactogenicity). Available vaccines and those under development fall short o f this ideal, thus stimulating new research in the field.
