What is the science behind mink and the coronavirus?

The coronavirus mutations triggered the culling of Denmark’s 17 million farmed mink.

Part of the country has been locked out after Danish authorities discovered genetic changes they believe could compromise the effectiveness of future Covid-19 vaccines.

More than 200 people have been infected with a coronavirus linked to mink.

And the UK has imposed an immediate ban on all visitors to Denmark over concerns over the new strain.

Danish scientists are particularly concerned about a strain of the virus linked to mink, found in 12 people, which they say is less sensitive to protective antibodies, raising concerns about vaccine development.

The World Health Organization said the reports are concerning, but more studies are needed to understand the implications for treatments and vaccines.

“We have to wait and see what the implications are, but I don’t think we should draw any conclusions about whether this particular mutation is going to have an impact on the effectiveness of vaccines,” said Soumya Swaminathan, scientist in chief.

The coronavirus, like all viruses, mutates over time and there is no evidence that any of the mutations found in Denmark pose an increased danger to people.

Dr Marisa Peyre, epidemiologist at the French research institute Cirad, said the development was “worrying”, but we do not yet know the full picture.

“Every time the virus spreads between animals it changes, and if it changes too much from the one circulating in humans right now, it could mean that any vaccine or treatment that will be produced soon might not work as well. that he should… do, ”she explained.

This is a very unusual chain of events: a virus that originally came from a wild animal, possibly a bat, jumped on humans, possibly via an unknown animal host, triggering a pandemic.

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Mink raised in large numbers on mink farms caught the virus from infected workers. And, in a small number of cases, the virus has “spread” from mink to humans, picking up genetic changes along the way.

Mutations in some strains linked to mink involve the virus spike protein, which is targeted by some vaccines in development.

“If the mutation is in a specific protein currently targeted by vaccine developers to trigger an immune response in humans, it means that if this new viral strain leaves mink and returns to humans, even with vaccination, the humans will start to spread and the vaccine will not protect, ”Dr Peyre told BBC News.

More than 50 million mink are reared for their fur each year, mainly in China, Denmark, the Netherlands and Poland. Outbreaks have been reported on fur farms in the Netherlands, Denmark, Spain, Sweden, Italy and the United States, and millions of animals have had to be slaughtered.

Mink, like their close relatives, ferrets, are known to be susceptible to coronavirus and, like humans, they can exhibit a range of symptoms, from no sign of illness to serious problems, such as pneumonia. .

Scientists suspect that the virus is spread in mink farms through infectious droplets, on food or bedding, or in dust containing feces.

The mink caught the virus from humans, but genetic detection work has shown that in a small number of cases the virus appears to have passed the other way, with the virus spreading from mink to humans.

Mink have become “reservoirs for the virus” and surveillance is needed in other potentially susceptible wild and domestic animals, said Professor Joanne Santini of University College London.

“Mink is the extreme, but it could be happening out there and we just don’t know it and it’s something we need to check out,” she told BBC News.

“What we do know is that minks get the virus from people; they can get infected and they spread among themselves and it comes back to humans.”

Danish scientists are conducting genetic studies on strains related to mink, and the genetic data has been shared with other researchers, in order to allow for further research.

“We have to find out where these mutations are and see what effect that has on the transmission of the virus and how infectious it is, because if it changes and is more infectious or has a wider host range, then that” is really pretty scary but maybe not, because we don’t know, ”said Professor Santini.

Some scientists have called for new restrictions on mink production, saying mink farming “hampers our response and recovery from the pandemic.”

In a recent letter to the journal Science, three scientists from Denmark, China and Malaysia wrote: “There is an urgent need to monitor, restrict and – if possible – ban the production of mink.”

WHO has called on all countries to step up surveillance and strengthen biosecurity measures around mink farms.

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