Animal-based studies have contributed to important findings and lifesaving medical advancements. The COVID-19 vaccines, for instance, were developed in animals, including mice and nonhuman primates. Animal models have also been critical in advancing AIDS drugs and in developing treatments for leukemia and other cancers, among many other uses.
But animal studies often fall short of producing useful results. They may weed out possibly effective drugs or miss toxicity in humans. They have failed to deliver breakthroughs in certain fields of medicine, including neurological conditions. A 2014 study estimated that candidate therapies for Alzheimer’s disease developed in animal models have failed in clinical trials about 99.6 percent of the time.
A growing, multidisciplinary community of researchers around the world is investigating alternatives to animal models. Some are motivated by concerns about animal welfare, but for many, sparing the lives of millions of creatures is just an added bonus. They are driven primarily to create technologies and methods that will approximate human biology and variability better than animals do.





















