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By Nikolaj Skydsgaard and Jacob Gronholt-Pedersen
COPENHAGEN (Reuters) – Denmark has discovered a new mutated strain of the coronavirus originating from mink farms in the northern part of the country, which authorities say could evade future COVID-19 vaccines.
To prevent human contagion, the government ordered the slaughter of the entire 17 million mink population in Denmark, one of the world’s largest mink fur producers.
Here is what is known about the Danish strain:
WHAT ARE MINK STRAINS AND WHY DO THEY MATTER?
Denmark has identified five variants of the virus that come from mink, but only one, known as Cluster 5, showed “reduced sensitivity” to antibodies, according to the Danish State Serum Institute (SSI), which deals with infectious diseases.
State epidemiologist Kare Molbak said group 5 was no more dangerous than other strains or more infectious.
Clusters 2, 3, and 4 are still being studied to reduce sensitivity, which has already been discarded in cluster variant 1.
HOW LONG HAS THE MUTATED VIRUS SPREAD?
Group 5 has been found on five mink farms in northern Denmark and 12 human cases were recorded in the same Danish region in August and September, but none have been recorded since, according to SSI.
“We can just hope that it no longer exists to the same extent,” Molbak told a news conference Thursday, adding that nothing can be said for sure.
Group 5 represents about 5% of the strains found in northern Denmark, but it has not turned up outside the country and it was not immediately clear why it arose in Denmark.
WHAT IS THE IMPLICATION FOR FUTURE VACCINES?
It is too early to say what impact, if any, the group 5 mutation might have on the efficacy of potential vaccines, Soumya Swaminathan, chief scientist at the World Health Organization, said on Friday.
But SSI’s initial lab studies show the new strain had mutations in its so-called spike protein, which invades and infects healthy cells.
This could pose a problem for future vaccines currently in development, as most of them focus on inactivating the spike protein.
Data has been shared with international counterparts, including WHO and the European Center for Disease Prevention and Control (ECDC), and the genome sequences of strains of the mutated virus have been registered with the Global Initiative to share all data. on influenza (GISAID).
SSI said it would continue to share its findings.
WHY IS THE VIRUS SPREAD AMONG THE MINK?
Mink appears to be susceptible to the new virus and “good reservoirs” for the virus, the WHO said Thursday. Outbreaks have occurred on mink farms in Denmark, the Netherlands, Spain and the United States.
Since minks are kept in cages very close to each other, the virus can spread easily.
WHY HUMANS?
Mink and humans have a similar biological trait regarding the so-called ACE2 enzyme expressed by cells of the respiratory tract, making it easier for mink to become infected with a virus that has adapted to humans, Allan Randrup Thomsen, virologist at Copenhagen University, he told Reuters.
Mike Ryan, the WHO’s leading emergency expert, said “There is always the possibility that this will come back to humans.”
“That is a concern because mammalian species like the mink are very good hosts and the virus can evolve within those species, especially if they are in large quantities packed together,” he said.
The new coronavirus is believed to have first jumped from animals to humans in China, possibly via bats or another animal at a food market in Wuhan.
ARE OTHER WINNERS AT RISK?
The risk is much lower in other farm animals, such as pigs and poultry, because farms have “very strict” biosecurity to prevent viruses from jumping the species barrier, the WHO’s Ryan said Friday.
The tests have failed to infect pigs, while cattle have been infected only to “a very small degree,” according to the Danish Food and Veterinary Administration.
He said a sample taken from the leg of a seagull tested positive for the new coronavirus, but there was no evidence that it had infected birds.
IS MUTATION A CONCERN?
Mutations in viruses happen all the time. Viruses survive by adapting to new environments, and most coronavirus mutations are harmless.
Two factors are involved in the mutation, Molbak said. First, the virus has to adapt to its new host. Second, when a virus enters a new population, many antibodies are created in the population, which is commonly known as herd immunity.
The virus responds by creating so-called antibody escape mutants, which try to avoid antibodies in the community.
WHAT ARE OTHER COUNTRIES AND WHO ARE DOING?
The WHO said it is looking at biosecurity around mink farms in countries around the world to prevent further “spillover events.”
The discovery of the mutation should not alter what governments and authorities around the world are doing to control the pandemic, he said Thursday.
The UK said on Friday that it would require all travelers arriving from the Nordic country to isolate themselves upon arrival as a result of the outbreak, but does not consider them a risk to the country.
(Additional reporting by Tim Barsoe, edited by Josephine Mason and Timothy Heritage)
