90-Second Read: Could a Hantavirus vaccine be on the horizon?

A single shot of an experimental mRNA vaccine completely protected animals against the deadly Andes Hantavirus, even at a fraction of the usual dose. When a rare, lethal virus broke out aboard a cruise ship this May and then scattered across two dozen countries with its passengers, it exposed an uncomfortable gap in the world's defences: there is no licensed vaccine or treatment for Andes Hantavirus. The finding, published in The Lancet, could offer protection against one of the few Hantaviruses able to spread between people. Andes virus is the exception as it is the only known member of the Hantavirus family that can pass from one person to another through close contact with respiratory secretions, such as coughing.

So far it has caused 13 reported cases and three deaths, but the wider worry is what came next. But none protects against Andes virus, and no Hantavirus vaccine of any kind is approved in the Americas or Europe. The researchers had already shown that two of their mRNA vaccine candidates could protect animals against Andes virus, but only after two doses given weeks apart. If you would like to republish this article, please follow these steps: use the HTML below; do not edit the text; include the author's byline; credit VaccinesWork as the original source; and include the page view counter script.

That capacity for spread between people has driven alarming clusters before, explain the authors. The ability to protect with so little vaccine matters because in an outbreak, the number of doses that can be squeezed from a limited supply can decide how many people get protected. The speed of the immune response opens a second possibility: using the vaccine not just to prevent infection, but to stop it in people who have already been exposed. With backing from the US National Institutes of Health, the UTMB team says it is working to speed the single-dose vaccines toward testing in people.

The vaccine uses the same basic design that powered the COVID-19 mRNA shots: genetic instructions that teach the body's own cells to make harmless pieces of the virus, in this case two surface proteins that train the immune system to recognise and fight the real thing. The team gave 30 hamsters a single injection of the vaccine, then exposed them to a lethal dose of Andes virus four weeks later. The shots triggered detectable antibodies within 14 days, fast by most vaccine standards.