Researchers at The University of Texas Medical Branch (UTMB) report the development of new vaccines that, in animal testing, provided full protection against the deadly Andes hantavirus after a single dose.
With backing from the National Institutes of Health, UTMB is working to fast-track these single-dose vaccines into human clinical trials.
The hantavirus drew public attention in May following an outbreak aboard the Dutch cruise ship MV Hondius. Unlike its viral cousins, the Andes virus can spread directly from person to person through coughing and close contact. Other hantaviruses are typically spread through contact with infected rodents. Because a person can carry the virus for weeks before showing any symptoms, health agencies face the complex challenge of identifying everyone who was exposed before they unknowingly pass it to others.
Using mRNA technology, researchers had previously created vaccines that successfully protected animals with a two-dose regimen. Recognizing that a fast-moving international outbreak doesn't allow time for patients to wait weeks between shots, the team retested the vaccines to determine whether a single dose would be effective.
The results exceeded expectations. When testing the vaccines in an animal model that mimics human disease, the scientists found that a single shot provided 100% protection against a lethal dose of the virus. Even when the researchers significantly lowered the dosage to a fraction of the original amount, the results remained definitive.
When the team examined the tissues from the vaccinated animals a month after infection, the virus was entirely gone. The vaccines triggered a powerful immune response, creating protective antibodies in as little as 14 days.
Because the Andes virus can take a relatively long time to make a human severely ill, these fast-acting vaccines could serve a dual purpose, possibly functioning as an emergency tool for people who have already been exposed.
Data from University of Texas Medical Branch at Galveston