Denmark set off alarm bells this week with its announcement that it is culling the nation’s entire mink herd — the largest in the world — to stop spread of the SARS-CoV-2 virus in the prized fur species because of potentially dangerous mutations.
Inter-species jumps of viruses make scientists nervous — as do suggestions of potentially significant mutations that result from those jumps. In this case, Danish authorities say they’ve found some genetic changes that might undermine the effectiveness of Covid-19 vaccines currently in development.
But is this latest twist in the Covid-19 saga reason to be deeply concerned? Several experts STAT consulted suggested the answer to that question is probably not.
“This hits all the scary buttons,” noted Carl Bergstrom, an evolutionary biologist at the University of Washington. But Bergstrom and others argued that while the virus’s penchant for infecting mink bears watching, it isn’t likely to lead to a nightmare strain that is more effective at infecting people than the current human virus.
“I don’t believe that a strain which gets adapted to mink poses a higher risk to humans,” said Francois Balloux, director of University College London’s Genetics Institute.
“We can never rule out anything, but in principle it shouldn’t. It should definitely not increase transmission. I don’t see any good reason why it should make the virus more severe,” he said.
Let’s take a look at what’s known about the Danish situation, why inter-species jumps make scientists nervous, whether the mutations are likely to affect vaccine effectiveness, and why Balloux thinks this situation is “fantastically interesting.”
What’s happening in the state of Denmark?
Denmark is the world’s largest producer of mink; it produces about 28% of the supply of this luxury fur.
Unfortunately, mink are susceptible to the SARS-2 virus, a fact that came to light in April when the Netherlands reported outbreaks on mink farms there. Infected humans who work in the farms transmit the virus to captive minks, which are housed in close quarters ideal for rapid transmission from mink to mink.
Occasionally, the mink infect people — a phenomenon recorded in both the Netherlands and in Denmark. In a statement, the Danish Ministry of Environment and Food said the country would cull its entire herd — estimated to be about 17 million animals — after finding mutations in the viruses from the mink that it believes would allow those viruses to evade the immune protection generated by Covid-19 vaccines.
Why do they think the mutated viruses would evade the vaccines?
Experts outside the country are not clear what that claim is based on. While there has been some information released about the mutations that have been recorded, it isn’t yet enough to support such a bold claim, said Marion Koopmans, head of virology at Erasmus Medical Center in Rotterdam, the Netherlands, where a lot of the analyses from viruses from the Dutch mink outbreaks have been conducted.
“That is a very big statement,” said Koopmans. “A single mutation, I would not expect to have that dramatic…