We should be concerned about the 'mink virus', but not for the reasons you think

Paranoia has lapped the globe after Denmark revealed it would cull its entire population of 17 million mink to stem the spread of a new Sars-Cov-2 mutation.

The variant, known as “cluster five”, was identified in a dozen people who fell sick in September. The discovery sparked drastic action after warnings the strain appeared resistant to antibodies in people who had previously been infected with Covid. 

According to experts at the Statens Serum Institut (SSI) in Copenhagen, cluster five could undermine a vaccine if it spreads internationally as the mutations are focused around the spike protein – which most immunisations target. 

There are similar concerns about a Covid strain identified by Glasgow University, named N439K, last week. 

Across the world authorities raced to respond, with Denmark putting seven municipalities in North Jutland, where the strain emerged, into lockdown in an effort to prevent a “new pandemic starting again, this time from Denmark.”

Meanwhile Britain banned entry to all non-resident foreigners coming from the Nordic country, while UK citizens returning from Denmark and their households must isolate for 14 days. Passenger planes, ships and lorries carrying freight from Denmark are no longer able to cross the border.  Hospitals were put on alert. 

But a string of experts have suggested concerns about vaccine efficacy are overblown. 

“While it’s not impossible that a single mutation could interfere with vaccine effectiveness, it’s unlikely,” Kristian Andersen, an immunologist at the Scripps Research Institute in  California, wrote on Twitter. 

Experts at the SSI were also quick to note that there is no evidence that the new variant is more contagious or serious.

Meanwhile the World Health Organization (WHO) has stressed that mutations are happening all the time and the vast majority do not change the fundamental behaviour of Sars-Cov-2. 

But that's not to say the grim decree to gas as many as 17 million mink across more than 1,000 farms is not prudent. 

“The decision by Danish authorities to cull its mink population is the right one, but not necessarily for the reasons given,” Dr Andersen said. “The 'mink mutant virus' stories have focused too much on the mutations and not enough on the fact that we have a raging Covid-19 epidemic in mink.”

Currently there is thought to be just one major reservoir of Sars-Cov-2: humans. This means it is still possible to suppress the virus. But control efforts would be greatly complicated if the virus gained a stronghold in animal populations, where it is much harder to track. 

The mink outbreak suggests this is a distinct possibility and is a stark reminder of the regularity of spillover events.

“I think the immediate danger is that this virus is now silently spreading in a captive bred species that's widely distributed and in dense colonies, like the mink,” said Peter Daszak, disease ecologist and President of the EcoHealth Alliance. 

“It would make it more difficult to stamp out the pandemic even with a vaccine, considering we'll probably not have perfect vaccine coverage and it may even be taken annually.”

But his concerns go well beyond Europe's mink farms. 

Across the globe millions of wild animals susceptible to human respiratory viruses - including civet cats, ferrets, racoon dogs, coypu and bamboo rats - are farmed in crowded conditions that could amplify the spread and evolution of Sars-Cov-2. 

In China, for instance, where wildlife farming was promoted as part of a poverty alleviation programme in the 1970s and 1980s, the 'industry' generated around US$77 billion dollars and employed 14 million people in 2016. 

If the virus does become widespread in these animals, cluster five could be just the first in a line of far more worrying mutations as the virus is pushed to evolve further. 

“This could lead to an attenuated (less virulent) strain, or a more pathogenic outcome for people,” said Dr Daszak. “Bottom line: creating new pathways for a nasty virus to evolve is not a good measure if we haven't yet got a vaccine. 

“The concern that is at the back of everyone's mind of course is the possibility that the virus could evolve in mink to the extent that it evades the new vaccines that come online soon,” he said. “That's unlikely, but the circulation of this virus in mink, it's ability to infect people from this reservoir, is a real problem.”

Given the huge number of animals intensively bred for meat and fur across the globe, efforts to identify which animals are and aren't susceptible need to be ramped up, Dr Daszak added. In spring, lab experiments ruled out pigs as a potential carrier of Covid, to huge sighs of relief from the pork industry.

But work to identify whether other commonly bred animals can carry Sars-Cov-2 has been limited. That could prove the biggest mistake of the pandemic to date. 

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