A single injection may be enough to stop one of the world's most dangerous emerging viruses in its tracks. Scientists at The University of Texas Medical Branch in Galveston have developed an mRNA vaccine that provided 100% protection against the deadly Andes hantavirus in animal trials—and with backing from the National Institutes of Health, they're racing to test it in humans.
The urgency is real. Unlike other hantaviruses that spread through contact with infected rodents, the Andes virus travels directly from person to person through coughing and close contact, making it a far more serious public health threat. That danger became sharply apparent in May when an outbreak aboard the Dutch cruise ship MV Hondius, departing from Argentina, infected 13 passengers and crew members and killed three. As infected travelers scattered across 23 countries, health agencies faced a chilling reality: people can carry the virus for weeks before showing any symptoms, unknowingly spreading it across the globe.
This threat is what drove Alexander Bukreyev, Ph.D., head of the Laboratory of Viral Pathogenesis and Vaccine Development at UTMB, and his team—including co-designer Ivan V. Kuzmin, Ph.D.—to reimagine their vaccine approach. They had previously created mRNA versions that protected animals, but those required two doses spaced weeks apart. In a fast-moving international outbreak, waiting between shots isn't an option.
When Bukreyev's team, led by researcher Michelle Meyer, Ph.D., tested whether a single dose could work, the results exceeded all expectations. In animal models that mimic human disease, one shot delivered complete protection against a lethal dose of the virus. The protection held even when researchers drastically reduced the dosage. "Every vaccinated animal remained completely healthy and showed no symptoms or weight loss," Meyer said. "When we looked at the tissues from the vaccinated animals a month after infection, the virus was entirely gone."
What made this breakthrough particularly striking was the speed. The vaccines triggered protective antibodies in as little as 14 days—a critical advantage given that the Andes virus can take weeks to cause severe illness in humans. That gap between exposure and severe symptoms opens a narrow therapeutic window that Bukreyev believes the vaccine could exploit.
"If given quickly to high-risk contacts during an outbreak, such as the Andes virus situation on the cruise ship, the vaccines could theoretically jump-start their immune systems fast enough to intercept the virus—stopping it from replicating and preventing them from getting sick or spreading it further," Bukreyev explained. In other words, this vaccine could work not just as prevention, but potentially as an emergency intervention for people already exposed.
The findings, published in The Lancet in 2026, now set the stage for human clinical trials. UTMB is working to fast-track the vaccine through that crucial next phase, turning laboratory success into a tool that could contain future outbreaks before they spiral into global crises. In a world where a single infected cruise ship passenger can reach dozens of countries within days, a single-dose vaccine that works fast may be exactly what public health needs.