Licensure of vaccines using the Animal Rule.

A number of new vaccines are being developed against microbial pathogens that might be used as bioweapons. For some of these vaccines, because of the lack of endemic disease and the lethal nature of the disease, human efficacy studies would not be ethical or feasible to conduct. In such cases, a regulation, known as the 'Animal Rule', can be used which allows the United States Food and Drug Administration to consider appropriate animal studies as evidence of effectiveness of a vaccine. Using this rule, pathways to licensure are being developed for new vaccines against bioweapons based on well-designed animal studies. The results of those animal protection studies together with the best scientific information available concerning immune mechanisms of protection allow protection in the animals to be bridged to effectiveness in humans, usually through the use of an appropriate immune marker. Published by Elsevier B.V.