Because they are our closest animal relatives, the use of chimpanzees in research has brought about both valuable advances for human health and intense ethical controversy. The US is one of very few countries that currently allow research on chimpanzees. Both the European Union and the UK already prohibit invasive research on chimpanzees. In 2010, the US National Institutes of Health (NIH), a key source of federal funds for all types of biomedical research, commissioned a study by the Institute of Medicine (IOM) to assess the necessity of using chimpanzees in research. The IOM report, issued in December 2011, found that “while the chimpanzee has been a valuable animal model in past research, most current use of chimpanzees for biomedical research is unnecessary.”

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The report recommended that the use of chimpanzees in research be guided by three main principles: the knowledge to be gained must be necessary to advance human health; that knowledge must not be obtainable using other animal models or human subjects; and the chimpanzees' housing environments must very closely match their natural habitat. Francis Collins, NIH director, accepted the recommendations of the IOM report and is developing a plan to implement them. Furthermore, Collins stated in a press release, “We will not issue any new awards for research involving chimpanzees until processes for implementing the recommendations are in place.”

The IOM report identified several research areas in which the use of chimpanzees may be justified, but a consensus was not reached on one particular research topic: the development of a vaccine against hepatitis C virus (HCV). As many as 170 million people worldwide have chronic HCV infections, which can lead to liver failure. HCV infects only humans and chimpanzees, and the IOM committee could not agree on which species should be used in the final tests of a prophylactic HCV vaccine.

Some researchers are concerned that the indecision may delay vaccine development. Christopher Walker (Nationwide Children's Hospital, Columbus, OH), who studies HCV immunity in chimpanzees, told Nature News, “If you have an idea for an entirely new approach to vaccination, but can't get proof of that principle in animals, my fear is that it will never move ahead into human trials.” And Thomas Rowell, director of New Iberia Research Center (LA), a large chimpanzee research center, told the New York Times, “Much of the work we do is done because the FDA won't allow the drug or vaccine to move into human trials without seeing data in relevant species.”