The U.S. Centers for Disease Control and Prevention (CDC) has reportedly ordered its internal researchers to halt all monkey studies. According to an exclusive report by the international journal Science on the 21st (local time), a senior CDC official who previously served in the Department of Government Efficiency (DOGE) under the Trump administration issued the directive.
The move is expected to be the first case since the National Institutes of Health (NIH) phased out chimpanzees from research a decade ago in which a government agency ends its own nonhuman primate program. Sally Thompson-Iritani, vice provost who oversees the University of Washington's animal care program, told Science it was "unprecedented."
Under this measure, studies involving about 200 macaque monkeys will end. The scientific community warned that stopping monkey experiments could disrupt research to prevent human immunodeficiency virus (HIV). The CDC used macaque monkeys in HIV prevention studies that address AIDS. The monkeys may be transferred to primate sanctuaries in the future, and some may be euthanized.
◇Part of the Trump administration's CDC overhaul
Since President Donald Trump took office in January, heads of major U.S. research agencies such as the Food and Drug Administration (FDA), the Environmental Protection Agency (EPA) and the NIH have announced plans to reduce reliance on animal testing. Government agencies are instead investing in new experimental tools such as organ chips, in which organ cells are seeded on plastic substrates, and Organoid, so-called "mini organs."
The CDC's halt of monkey experiments is seen as reflecting President Donald Trump's intent to overhaul the CDC. Science reported that Sam Beyda, who came from DOGE, issued the stop order. Shortly after taking office, the Trump administration created DOGE to reduce federal regulations and expenditure. In its early days, DOGE was led by Tesla Chief Executive Officer (CEO) Elon Musk.
Beyda was recently appointed deputy chief of staff at the Department of Health and Human Services (HHS), the parent agency of the CDC. The chief of staff's office supports the CDC Director General and coordinates agency-wide priorities and policies. According to Bloomberg, Beyda was also named the overall lead for several plans to restructure the CDC.
According to a CDC official, Beyda represents the position of Health and Human Services Minister Robert F. Kennedy Jr., who recently made the reduction of animal research part of the "Make America Healthy Again" agenda. Minister Kennedy has criticized the CDC for representing the pharmaceutical industry's position.
The CDC was shaken significantly as the Trump administration took office. In Aug., former Director General Susan Monares was dismissed after pushing back on Health and Human Services Minister Robert F. Kennedy Jr.'s anti-vaccine claims. The CDC is currently led by Health and Human Services Vice Minister Jim O'Neill. Although O'Neill worked within HHS under the George W. Bush administration, he has little experience in the medical field.
Beyda likewise has little background in science or medicine. Beyda earned an economics degree from Columbia University in 2023 and is only known to have volunteered for a clinical trial of a COVID-19 vaccine in 2020.
◇"A fatal blow to research on preventing sexually transmitted infections"
Science said the CDC did not directly answer questions about the monkey program. However, a CDC Spokesperson said by email that "the CDC regularly evaluates its research project portfolio, including nonhuman primate research, and strives to use nonanimal research methods when possible," according to the report.
The animal-testing opposition group "White Coat Waste Project" called the decision "a far more positive outcome than expected" and said it "will set a standard for other agencies." The scientific community, however, warned that the move is a major mistake. Although papers have repeatedly reported that organ chips or Organoids yield results similar to those from human cells or animal testing, there are still experiments that require monkeys.
For example, thalidomide, which a German pharmaceutical company once developed as a remedy for morning sickness, later caused the grave side effect of births with deformities. At the time, tests were run only on dogs; had tests been conducted on monkeys, which are closer to humans, the side effects might have been known in advance. Scientists say monkey studies are unavoidable to confirm the efficacy and side effects of new preventive drugs for sexually transmitted infections such as HIV and sexually transmitted diseases.
In fact, the scientific community credits the CDC's monkey research program with helping drive a sharp global decline in infection rates by developing HIV preventive measures. Demetre Daskalakis, former head of HIV prevention at the CDC, said, "The monkey research program also evaluated the effectiveness of several other sexually transmitted infection preventive measures," adding, "If disease-prevention drugs that Merck (MSD) or Gilead develop in the future do not start at the CDC, it is hard to say where they will be born."
The CDC's monkeys are already being used in several research programs to develop preventive medications. If the research ends early, researchers said the results achieved so far will be lost and investments wasted. Deborah Fuller, director of the Washington National Primate Research Center who has studied HIV for 30 years, also said, "This move is a tremendous loss to the field of HIV research," adding, "The CDC's monkey studies have been at the forefront of developing microbicides that protect women from HIV."
The monkeys' ultimate fate is uncertain. CDC researchers, urging a gradual phaseout of monkey experiments to continue their work, asked that the animals be transferred to primate research centers run by universities or other government agencies. However, Science reported that HHS is pursuing a plan to fully halt research and retire the monkeys from laboratories within a year.
References
Science (2025), DOI: https://doi.org/10.1126/science.zd25zhr