The US has significantly tightened its rules on the use of chimpanzees in medical research, ruling it out except for cases in which there's no other valid testing method.
The National Institutes of Health says that new grants for testing on chimps will only be given where there's no other suitable model, and where it's impossible to test ethically on humans.
In addition, it should be allowed only if doing without will prevent or significantly hinder work to prevent or treat life-threatening or debilitating conditions.
Under these criteria, testing on chimpanzees will be all but banned altogether.
"The committee concluded that research use of animals that are so closely related to humans should not proceed unless it offers insights not possible with other animal models and unless it is of sufficient scientific or health value to offset the moral costs," says committee chair Jeffrey Kahn of the Johns Hopkins Berman Institute of Bioethics in Baltimore.
"We found very few cases that satisfy these criteria."
When it comes to behavioral research, the rules have also been made more stringent. Studies involving chimps should give insights into normal and abnormal behavior, mental health, emotion or cognition that couldn't be provided in any other way.
Studies must be carried out only on acquiescent animals, minimally invasive, and applied so as to minimize pain and distress. Animals used in either biomedical or behavioral studies should be looked after in appropriate environments or in natural habitats.
The committee says it's reached its decision because advances in the development of other research tools and methods - such as cell-based tests and other animal models - have rendered chimpanzees largely redundant.
It says it can only think of two possibly-valid ongoing uses: the development of a limited number of monoclonal antibody therapies already in the pipeline, and development of a vaccine that would prevent hepatitis C infection.
In the first case, there's ongoing work that should probably be allowed to finish; in the second, there's the fact to consider that chimps and humans are the only two species susceptible to Hepatitis C.
The committee makes the point, though, that chimps could be needed in future for research into as yet unknown diseases or disorders.
The Humane Society of the United States has welcomed the news.
"Chimpanzees have provided limited value in research settings, and now alternative methods have been developed that will make their use all but obsolete," says president and CEO Wayne Pacelle.
"When one takes into account the scientific findings of the IOM, along with the obvious financial and moral costs of using chimps in invasive experiments, then there’s only one reasonable conclusion: it’s time to end the use of chimps in harmful, invasive research."