Image : Analysis shows that the mutated covi (short for novel coronavirus, SARS-CoV-2, CCP virus) in mink may not be harmful to the SARS-CoV-2 vaccine. Scientists believe that the rapid spread of covi in the mink population does not mean that they will still be culled in large numbers. (Photo credit: Ole Jensen/Getty Images)
Recently, after announcing that the mutant covi may threaten the effectiveness of the vaccine, the Danish health department released relevant experimental data. The mutant covi spreads in mink farms mink and humans. Denmark has culled about 17 million minks in November.
In the published data, the researchers sequenced virus samples from 40 mink farms and identified 170 covi variants. In human virus samples, about 300 viruses can be traced back to mink covi variants, which means that the mutation first originated in mink.
However, researchers who reviewed the data found that there is almost no evidence that the mutated virus is more deadly, spreads more easily in the population, or poses a threat to the effectiveness of the vaccine. They urged not to over-interpret preliminary and limited experimental data.
In the mink and human covi samples, the researchers found several mutations in the covi spike protein gene, which are related to the virus invading cells. This has aroused the attention of scientists, because changes in this area will affect the immune system's ability to resist. Many vaccines also play a protective role by training the immune system to block the spike protein.
Among the mutant covi is a variant called "Cluster-5", which causes three amino acid changes and two deletions in the spike protein. This variant is found in the Jutland region of northern Denmark and detected in 5 farms and 12 people. Preliminary cell experiments have shown that antibodies carried by some covid survivors are more difficult to recognize this variant. Considering many reasons, the Danish authorities decided to cull the minks.
However, after reviewing the public data, some researchers said that in the case that the "fifth cluster" variant has not been widely spread, claims about its transmission capacity or fatality rate are speculative.
"The virus mutations that we know about mink-related viruses cannot be associated with rapid transmission or any changes in morbidity and mortality." Astrid Iverson, a virologist at the University of Oxford, UK , said.
Since June this year, more than 200 farms have detected SARS-CoV-2. Iverson said that the animals on the farm may become a source of huge viruses that easily infect humans. In areas affected by mink farming, the number of people infected with covi has shown a large increase. So the culling of mink is necessary.
So far, a variant of the covi related to mink, Y453F, has spread widely among the population. In patient samples from Denmark, the variant was found in about 300 sequences, and the variant could not be detected by commercial monoclonal antibodies but Iverson said that this does not mean that mutations will hinder the efficacy of the drug.
David Robertson, a virologist at the University of Glasgow in the United Kingdom, also pointed out that the mutations currently detected in humans and mink can not be confirmed whether the mink is the source. It is not clear how the new crown virus entered Farm or breeding farm. However, there are also views that some mutations may have been transmitted to humans by mink, so if the transmission path of mink is not controlled, problematic mutations are more likely to occur.
In Europe, outbreaks have occurred in mink farms in the Netherlands, Sweden, Spain, and Italy. The Netherlands has planned to eliminate all mink populations by 2021, and plans to terminate mink farming by 2024.
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