06-11-2020 by Mirai
Millions of minks are currently slaughtered in Denmark. The SARS-CoV-2 coronavirus would have mutated on contact with these small mammals and infected several humans, which could compromise the development of vaccines against Covid-19.
The discovery of two viral mutations of Sars-CoV-2 in 5 mink farms and the transmission of the mutated virus to 12 people led the Danish health authorities to decide the immediate culling of all minks raised on their territory, that is, close to of 17 million animals.
These small carnivorous mammals, bred for their fur, are in the crosshairs of the Danish, but also Dutch and Spanish authorities. The spread of the coronavirus by aerosols would have been favored by the high density of animals in livestock houses.
The S1 protein of SARS-CoV-2 would have mutated
The coronavirus identified in the Danish mink would differ slightly from the SARS-CoV-2 observed in humans. In the case of the Danish mink, the 2 mutations in the gene encoding the Sars-CoV-2 protein S1 were reported as of September 4 by the Statens Serum Institute in Copenhagen.
"The plasticity of the S1 protein gives the virus a decisive advantage when it comes to crossing the species barrier. It justifies the surveillance of viruses isolated from animals, particularly mink, since it is the only species for which the Covid-19 transmission has been observed from animals to humans, "warn the National Academy of Medicine and the Veterinary Academy of France.
According to the Danish authorities, people infected with the SARS-CoV-2 mutant would not have presented more serious symptoms. However, their antibodies would react differently: "They still have an effect, but not as effective," said Danish Health Minister Magnus Heunicke.
This mutation could jeopardize vaccination
Researchers are currently working on developing a vaccine from known SARS-CoV-2 strains and antibodies capable of neutralizing the virus. Health authorities fear that this vaccine will be ineffective if the mutated version of SARS-CoV-2 spreads in the human population.
However, no one can yet assess the dangerousness of this mutation. Some known viruses mutate from year to year, eluding the efficacy of vaccines, while others evolve without succeeding in thwarting them. Scientists remain even more cautious as the data the Danish government relies on has yet to be made public.
Strengthen biosecurity measures
The Danish governments decision may seem cruel, but it seems necessary for health authorities to avoid any risk of further spread of the mutant virus. The latter recommend:
reinforce epidemiological surveillance of animal coronaviruses, particularly in mustelids (minks and ferrets);
ensure that the slaughter of minks has made it possible to permanently halt the spread of the virus variant isolated in Denmark;
to detect any mutation between SARS-CoV-2 isolated from animals, particularly mink, that may limit the effectiveness of future vaccination against Covid-19;
implement the strictest biosecurity measures in mink farms that are still free in other countries;
It is recommended to avoid any contact between people potentially infected with SARS-CoV-2 and their pets, especially ferrets, and maintain the same barrier measures as for people around them (wearing a mask, washing hands).
In France, the four mink farms have been put "under surveillance" since the beginning of June 2020, the Ministry of Ecological Transition told AFP on Thursday (November 5). Mortality surveillance has been established and "biosecurity measures are already being strengthened on these farms."
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