Refinement of vaccine potency testing with the use of humane endpoints.

Public concern over the use of laboratory animals has increased in recent years. Laboratory animal procedures involving unrelieved pain and distress (e.g., the footpad injection of rodents with Freund's adjuvant), which were routine in the past, now require strong justification. Moral concern is reflected in the existing legislation on animal experimentation in the United States (CFR 1992) and in Europe (Council of Europe 1986) and in the publication of an increasing number of best practice codes (e.g., on immunization protocols). In many countries since the early 1990s, animal ethics committees have been established, housing conditions have been improved, and training curricula have been implemented for those working with laboratory animals. Published results of a poll taken in the United Kingdom about public views on animal experimentation (Aldhous et al. 1999) reveal that people provided with impartial information appear to weigh the pros and cons of each experiment carefully before deciding whether they are willing to support the use of animals in research. The results also reveal that potential distress is an important factor in the public's support of specific uses of animals. Death may be used as the experimental endpoint in cancer research, studies of infectious disease, carcinogenicity and toxicology (e.g., the LD50 test), drug comparisons, and vaccine potency testing (Hamm 1995). In this article, we discuss humane endpoints that can replace lethality as an endpoint in vaccine potency testing.