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On May 18, 2026, the Centers for Disease Control and Prevention (CDC) announced a travel ban affecting foreign nationals who have been in the Democratic Republic of the Congo, Uganda, or South Sudan within the past 21 days. This decision was made in response to a spreading outbreak: at least 80 suspected deaths from the Ebola Bundibugyo virus, with multiple Americans exposed during relief work in the affected areas.
Travel restrictions are often a necessary tool in these instances. Enhanced screening, laboratory capacity, and hospital readiness are the front line of outbreak response. But a less visible part of that defense is the research infrastructure that allows us to develop vaccines and treatments when disease emerges.
That infrastructure just shrank dramatically.
Six months before this outbreak, the CDC was ordered to shut down all of its nonhuman primate research. The directive, issued in November 2025, will retire approximately 200 macaque monkeys currently used in studies on HIV, hepatitis, and other infectious diseases. It marks an abrupt and sweeping move: the wholesale end of a federal agency’s in-house primate research program.
The decision was fast, and the justifications seemed clear: concerns about animal welfare, taxpayer funding, and the availability of alternative research methods. These are legitimate conversations to have, but the timing raises a harder question: What is the cost of hasty policy decisions when infectious diseases do not wait for bureaucratic planning?
Why Nonhuman Primates Matter for Infectious Disease
The case for nonhuman primate research in the fight against Ebola is not theoretical. It is written in the history of vaccine and treatment development.
When Ebola first emerged as a human threat, researchers could not ethically test candidate vaccines and treatments on people without first understanding their safety and efficacy in an animal model that closely resembles human biology. Rodent models, mice and guinea pigs, provided initial data. But nonhuman primates were essential for the critical next step.
When researchers tested vaccine candidates that had worked well in mice and guinea pigs, a surprising problem emerged: those same vaccines failed to protect nonhuman primates. The way Ebola manifests in primates turned out to be fundamentally different from its patterns in rodents. This gap revealed a critical limitation of smaller animal models, which was that they cannot reliably predict how vaccines will perform in species with biology more similar to humans. Understanding primate responses required studying primates directly.
This finding is precisely why nonhuman primate research is irreplaceable. The similarities between monkey and human biology that make rodent models unsuitable for the final critical safety step are the same ones that make primate models predictive of human outcomes. Without nonhuman primate studies, there would have been no way to know whether candidate vaccines and treatments would work in people before human trials began. Today, we have effective vaccines against other Ebola species, along with promising candidate treatments being investigated against the current Bundibugyo variant, because researchers conducted rigorous, difficult work in nonhuman primates when smaller animal models proved insufficient.
The Shutdown and Its Timing
Last November, the CDC was ordered to cease all primate research. The decision was made quickly, with minimal input from the scientific community or from the National Primate Research Centers, which have decades of experience managing such transitions.
What followed has been chaos.
Officials scrambled to identify sanctuary placements for the retiring animals. One proposal, to transfer up to 162 of the roughly 200 macaques to a sanctuary in Texas that already houses large troops of monkeys, has drawn sharp criticism from animal welfare experts and facility directors. Their concern is not that the animals should stay in research, but that the transition plan appears to prioritize speed over animal safety.
Animal welfare experts raise a critical concern: rapidly placing animals accustomed to solitary or pair living into large, established social groups without careful integration planning creates a genuine risk of serious injury. The speed of the proposed transition prioritizes removing animals from research over ensuring their safety in the new environment. Additionally, unlike federally regulated research centers, the proposed sanctuary is not subject to USDA oversight or regular, publicly available welfare inspections. It holds private accreditation, though those inspection reports are confidential. The transition timeline remains undefined, and the proposal does not specify how the transfer or the animals’ lifetime care would be funded.
So we face an uncomfortable reality: in the name of ending animal research, the hasty policy decision now threatens the very animals it intended to protect. The monkeys face potential harm during transition, and the research capacity to respond to emerging infectious diseases has been reduced.
The Larger Question
This is not an argument that animal research should never be scrutinized, or that policy should never change. The ethical questions surrounding nonhuman primate research are real and deserve honest and open discussion. There are legitimate reasons to explore alternatives, refine protocols, and ensure the highest standards of care. However, there is a difference between thoughtful policy change and hasty mandate. One involves stakeholders, timelines, and contingency planning. The other creates exactly the situation we now face: animals at risk during transition, research capacity lost, and an active outbreak reminding us why that capacity matters.
In past outbreaks, healthcare workers and aid personnel in Central Africa have survived because Ebola vaccines and treatments exist. Those tools exist because nonhuman primate research, however difficult and morally complex, was conducted when no alternative was sufficient.
Today, as the CDC mobilizes to respond to Ebola (including recently announcing they are exploring promising treatments tested in nonhuman primates), the absence of its own research capacity is not an immediate emergency; other facilities and international partners are involved in response efforts. But it is a reminder of what we lose when policy decisions are made in isolation from scientific reality, and what we risk when we assume that the diseases that threaten us will wait patiently while we reorganize our defenses.
Public health requires preparedness, and preparedness requires research capacity.
Research capacity requires difficult, ethically grounded choices.
Shutting down that capacity in the name of a faster, simpler policy is understandable. But when the next outbreak comes, it will feel less so.
References
Centers for Disease Control and Prevention. (2026). Ebola disease: Current situation. Retrieved May 23, 2026, from https://www.cdc.gov/ebola/situation-summary/index.html
Geisbert, T. W., Pushko, P., Anderson, K., Smith, J., Davis, K. J., & Jahrling, P. B. (2002). Evaluation in nonhuman primates of vaccines against Ebola virus. Emerging Infectious Diseases, 8(5), 503-507. https://doi.org/10.3201/eid0805.010284
Merelli, A., & Branswell, H. (2026, May 18). U.S. bans entry from Ebola-affected countries as American patient is identified. STAT News. https://www.statnews.com/2026/05/18/cdc-ebola-travel-ban-announced-uganda-congo-south-sudan/
Grimm, D. (2025, November 21). Exclusive: CDC to end all monkey research. Science. https://www.science.org/content/article/exclusive-cdc-end-all-monkey-research
Grimm, D. (2026, May 15). CDC plan to retire lab monkeys to Texas sanctuary draws ire. Science. https://www.science.org/content/article/cdc-plan-retire-lab-monkeys-texas-sanctuary-draws-ire