Enlarge / A curious pair of black-footed ferret kits survey the shortgrass prairie from their outdoor enclosures at the National Black-footed Ferret Conservation Center in Colorado. (credit: Ryan Moehring | US Fish and Wildlife Service (CC BY-2.0) )

In late summer, as researchers accelerated the first clinical trials of COVID-19 vaccines for humans, a group of scientists in Colorado worked to inoculate a far more fragile species.

About 120 black-footed ferrets, among the most endangered mammals in North America, were injected with an experimental COVID vaccine aimed at protecting the small, weasel-like creatures rescued from the brink of extinction four decades ago.

The effort came months before US Department of Agriculture officials began accepting applications from veterinary drugmakers for a commercial vaccine for minks, a close cousin of the ferrets. Farmed minks, raised for their valuable fur, have died by the tens of thousands in the US and been culled by the millions in Europe after catching the COVID virus from infected humans.

Enlarge (credit: Eric Sonstroem / Flickr )

Did anyone have "mink farms" on their 2020 catastrophe bingo cards? It turns out that the SARS-CoV-2 virus readily spreads to mink, leading to outbreaks on mink farms in Europe and the United States . Denmark responded by culling its entire mink population, which naturally went wrong as mink bodies began resurfacing from their mass graves, forcing the country to rebury them . Because 2020 didn't seem apocalyptic enough.

More seriously, health authorities are carefully monitoring things like mink farms because the spread of the virus to our domesticated animals raises two risks. One is that the virus will be under different evolutionary selection in these animals, producing mutant strains that then pose different risks if they transfer back to humans. So far, fortunately, that seems not to be happening . The second risk is that these animals will provide a reservoir from which the virus can spread back to humans, circumventing pandemic control focused on human interactions.

Heightening those worries, mid-December saw a report that the US Department of Agriculture had found a wild mink near a mink farm that had picked up the virus, presumably from its domesticated peers. Fortunately, so far at least, the transfer to wild populations seems very limited.

Enlarge / Coronavirus has swept through mink farms in Europe. (credit: Getty | Viktor Drachev )

The pandemic coronavirus has made its way onto two mink farms in Utah, leading to “unusually large numbers” of dead animals, according to a Tuesday announcement by the US Department of Agriculture.

These are the first reported cases of the coronavirus, SARS-CoV-2, infecting mink in the country. For months, authorities in European countries, including the Netherlands, Denmark, and Spain, have reported outbreaks in mink pelt farms, leading to the culling of more than a million of the soft, furry mammals. From laboratory experiments, it’s also clear that ferrets, a relative of minks, are also readily infected with the novel coronavirus.

The affected farms in Utah reported cases of COVID-19 in people working on the farms, who may have spread the infection to the animals.