Scientists in the UK are working to secure samples of a mutant form of coronavirus that arose in Danish mink farms and spread into humans, prompting ministers to ban non-UK citizens arriving from Denmark.
Danish health authorities raised the alarm over the mutant virus last week and announced a cull of the nation’s 17 million mink as the Statens Serum Institut (SSI) in Copenhagen warned of potentially “serious consequences” for vaccines if it was allowed to spread internationally.
Tests in Denmark have picked up more than 200 people with coronavirus mutations linked to mink farms since June, but concern centres on a dozen cases in North Jutland of people who fell ill in September with a unique variant of the virus.
Known as “cluster five”, the variant has four separate mutations in the so-called spike protein that the virus uses to enter cells, and on which most vaccines are based.
Researchers at the SSI found that antibodies from people who recovered from coronavirus were less effective at neutralising the mutant strain, but have not made details of their experiments public. There is no evidence that the virus, found on five Danish mink farms, spreads more easily or causes more severe disease in humans than common strains of the virus.
While the Danish scientists believe the mutations are concerning because of their potential to make vaccines less effective, one expert told the Guardian the fears were overblown and that the cluster five variant might already have died out in humans.
Eight of the dozen cases in Denmark had direct contact with the mink farming industry, with only four identified in the local community.
Amid the uncertainty, scientists advising the UK government took part in talks over the weekend to acquire samples of the mutant virus from the Danish authorities. The virus will go through a series of tests to investigate whether or not it evades antibodies from recovered patients and those enrolled in vaccine trials.
Further experiments will focus on how well the mutant virus grows in human cells, how well it may spread between humans, and why the mutations arose in the first place. At least six countries, including Denmark, Spain, Sweden, Italy, the Netherlands and the US, have reported outbreaks of coronavirus in mink farms.
Prof Peter Openshaw, a member of the UK government’s New and Emerging Respiratory Virus Threats Advisory Group, said the mutations may be nothing more than the virus evolving to spread in mink, but added that it was sensible to shut down the spread “as a matter of caution” until scientists had more evidence.
“It could be that the mutations mean something in terms of mink to mink transmission, but are irrelevant to human transmission,” he said.
Prof Francois Balloux, the director of UCL’s Genetics Institute said mink are highly susceptible to coronavirus, and since they outnumber humans three to one in Denmark, it was sensible to cull the animals to prevent them fuelling the epidemic.
Balloux criticised what he called “alarmist” messaging from Denmark over the threat the mutations posed, and said the cluster five variant may well have died out in humans because it failed to spread effectively.
“I really don’t think we should be particularly concerned about them. There are many other mutations not acquired in mink that are more concerning in terms of vaccine escape,” he said. One such mutation, known as N439K, has already been found to confer some resistance to antibodies.
A Department of Health and Social Care spokesperson said there was no evidence the new strain had spread from Denmark to the UK, adding: “While there have been some reports of mink to human transmission, we do not consider this a risk as there are no fur farms in the UK.
“We are working closely with international partners to understand the situation in Denmark and we continue to keep the situation under review,” they said.