Difficulties associated with the development and licensing of vaccines for protection against bio-warfare and bio-terrorism.

Today there is an increasing need to license vaccines for the protection of individuals against bio-warfare and bio-terrorism. While the need is apparent, the actual road to developing, producing and licensing such vaccines successfully is as yet undefined. Bio-defence vaccine candidates may come from several sources. They may come from vaccines that were previously licensed but are no longer in production, vaccines that are currently in an IND status, vaccines currently licensed in foreign countries, and newer vaccines currently under development. The issues that apply to the development and licensing of these vaccines can be defined by currently accepted standards for manufacture, and the requirement to demonstrate safety and efficacy to a level that gives the scientific and medical community, regulatory agencies, users and the public at large confidence. Requirements for manufacturing and demonstration of safety will be consistent with vaccines being developed for traditional purposes. However, demonstration of efficacy will be more difficult. Because field trials for these vaccines are generally not feasible and the conduct of human challenge studies is generally considered unethical, the demonstration of efficacy will need to be based on existing efficacy data, a thorough understanding of both the disease's pathogenesis and mechanism of protection, the ability to identify surrogate markers for efficacy, and the use of the proposed FDA "animal rule".