Veterinary workers have begun the gruesome business of gassing and then burning 17 million mink in Danish farms in a bid to halt further spread of a Covid-19 mutation from the animals to humans.
The decision to cull the country’s mink population was made after several hundred people became infected with a new strain of Covid-19 that had infected the animals. Researchers have warned this strain could be more resistant to vaccines.
Yesterday, Britain banned arrivals from Denmark in an effort to contain the new strain amid fears that another jump by the virus from animals to humans could make Covid-19 even more deadly. Scientists have urged caution about the dangers. “I don’t think we should come to any conclusions about whether this particular mutation is going to impact vaccine efficacy,” said Soumya Swaminathan, the WHO’s chief scientist. “We don’t have any evidence at the moment that it would.”
James Wood, professor of veterinary medicine at Cambridge University, agreed: “If the reports of nearly 800 people being infected with the mutated strain are confirmed, it is highly likely this scale of transmission will have been driven by person-to-person transmission rather than from direct mink-to-person transmission. That means culling mink may not in itself cause the strain to disappear, but it may stop further mutant strains from developing in that species.”
Five other nations – Spain, Italy, the Netherlands, Sweden and the US – have also reported Covid infections in mink though it is not clear if these have been caused by mutated strains of the virus. Denmark is the world’s biggest producer of mink, and the cull will effectively end that industry, a development that has delighted animal welfare groups.
It is also a reasonable precaution, say scientists. “The danger is that the mutated virus could spread back into humans and evade any vaccine response designed to the original, non-mutated version of the spike protein,” said Ian Jones, professor of virology at Reading University. “Of course, the Mink version may not transmit well to man so it’s a theoretical risk but Denmark is clearly taking a precautionary stance so that this possibility is avoided or made much less likely.”
Other scientists dismissed the dangers. “I don’t believe that a strain which gets adapted to mink poses a higher risk to humans,” Francois Balloux, director of University College London’s Genetics Institute, told the health website Stat. “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.”