Is a dangerous new coronavirus strain circulating in farmed minks?

The Danish government has ordered the slaughter of all farmed mink in the country after the reported discovery of a mutant form of coronavirus in the animals. It has already spread to humans.

[A disturbing story on many fronts. Travellers from Denmark now required to quarantine – Owl]

Graham Lawton www.newscientist.com 

What do we know about the situation in Denmark?

According to a report in the Danish newspaper Berlingske, 207 mink farms have seen infections of coronavirus. The authorities have failed to contain the virus, and all 17 million farmed mink in Denmark will now be culled, said Denmark’s prime minister Mette Frederiksen at a press briefing on 5 November. Denmark has the world’s largest mink industry.

The Danish prime minister described the mutated virus as “a serious risk to public health and to the development of a vaccine.” However, health minister Magnus Heunicke told the press briefing that there is no sign yet that the mutant virus causes more serious symptoms of covid-19.

Some areas of northern Jutland – the region of Denmark that connects to the European mainland – will be isolated to stop the spread of the virus in humans. Frederiksen said a “mutant” virus has been identified in five farms and 12 people have become infected with it.

What sort of mutant?

We don’t know for sure. There is no scientific publication about it. According to the newspaper report, the Danish State Serum Institute says the virus is sufficiently different from other circulating strains to mean that a vaccine may not work against it, though there is no information on the Institute’s website and it has not yet responded to New Scientist’s requests for comment. Up to now all circulating strains are thought to be similar enough that a single vaccine will immunise against all of them.

The newspaper also said that the 12 infected people “have been found to have an impaired reaction to antibodies.” It is not clear what this means. It could be a mistranslation of “antibody response”, which could mean that the 12 individuals are producing previously unseen antibodies. That would strengthen the claim that the mutant virus may evade a vaccine.

Can mink really catch the coronavirus?

Yes. There are already scientific reports of farmed mink in the Netherlands catching it from humans. And in June more than 90,000 mink were culled in Aragon, Spain after the virus was detected in fur farms.

Can mink pass it to humans?

Yes. One of those reports from the Netherlands says that at least one worker on a mink farm caught the virus from the animals. The worker showed only mild respiratory disease.

What do scientists say?

Francois Balloux, a professor of genetics at University College London (UCL), took to Twitter to describe the report as “highly problematic”. He said his colleague Lucy van Dorp at UCL has already documented numerous coronavirus mutants arising repeatedly in mink, none of which are concerning for humans. The claim that this strain may be resistant to a vaccine is “idiotic”, he said. Such mutations might emerge in humans once we have a vaccine but won’t appear in mink, he said.

Other scientists echoed his views. James Wood at the University of Cambridge in the UK, said he understands that the mutation is on the spike protein, which the virus uses to enter cells and which induces an antibody response. However, “the true implication of the changes in the spike protein have not yet been evaluated by the international scientific community and are thus unclear. It is too early to say that the change will cause either vaccines or immunity to fail,” he said in a statement.

Virologist Ian Jones at the University of Reading in the UK, said that it was not surprising that the virus had mutated, as it would need to adapt to mink. Denmark’s precautionary action would make it less likely that the new virus would spread widely in humans, he said in a statement.

Is the virus likely to spread to other animals?

Yes, very. More than 60 mammal species are known to be definitely or probably susceptible, ranging from gorillas and chimps to foxes, yaks, giant pandas and koalas. Even some whales, dolphins and seals may be able to catch it.

Why did nobody see this coming?

We did. Even before this happened, virologists were concerned about “reverse spillover”, which is when humans pass the virus on to domestic or wild animals. That could be a problem for the animals as some species fall ill and die. It could also spell trouble for us, as animals could become a new reservoir of virus and make the pandemic even harder to control. Animals could also be a crucible for the virus to mutate into another novel coronavirus.

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