Coronavirus mutations identified in mink farms could hamper the effectiveness of vaccines currently under development, the European Centre for Disease Prevention and Control (ECDC) has warned.
Although there is "high uncertainty" as to the nature of such mutations, identified following outbreaks on mink farms in Denmark, the ECDC said that if the mutated virus spread widely in the human population it could compromise vaccine effectiveness.
If the virus established itself in mink populations it could also give rise to "problematic virus variants in the future".
In a statement, the EU's disease control agency said Covid-19 can spread from humans to minks and vice versa.
Because of the difference between minks and humans the virus can mutate quickly in minks before reinfecting humans, the ECDC said.
"When the virus is introduced into a mink farm, it can spread quickly leading to many cases among minks. Due to the large number of infections and possibly due to biological differences between minks and humans, the virus can accumulate mutations more quickly in minks and spread back into the human population," the agency said.
Antibodies would be less effective in targeting such variations, and this could impact the ability of future vaccines to work, the agency said.
The ECDC said: "If these new SARS-CoV-2 variants, with lower susceptibility to neutralizing antibodies, spread widely in the population it could potentially affect the level of overall vaccine effectiveness of vaccines under development, and that the establishment of a virus reservoir among minks may give rise to problematic virus variants in the future".
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The agency said "further investigations" were needed in order to understand the mutations and their implications for reinfections and the spread and severity of the virus, as well as for vaccine effectiveness.
The Stockholm-based agency said that on 5 November, Denmark reported 214 cases of people infected with Covid-19 mutations related to infected mink on a number of mink farms.
The variants were also found in people living in the affected areas. In all, 12 human cases reported in Northern Jutland in August and September were infected with strains showing four genetic changes in the virus's "S" protein.
The ECDC says that not all the individuals infected had had a direct link with a mink farm, suggesting the transmission of the new variant from human to human.
The agency said national authorities across Europe should increase testing among mink farm workers and communities associated with mink farms.
Sequencing and exploring antibody properties and virus infectivity should also be carried out, as well as measures to prevent infection among mink farm workers and visitors.
The authorities should also carry out animal testing and prevent the spread of the virus from animals to humans, the ECDC urged.
Meanwhile, the top US government scientist has said the new virus strain that has spread from mink to humans does not look as though it will currently stop Covid-19 vaccines from working.
Dr Anthony Fauci said the issue needs to be taken seriously but indications at the moment were that the mutations would not derail plans for mass vaccination.
He said: "Whenever you see something like that you need to pay attention to it. You certainly can't just blow it off.
"You have got to look at it, you have got to take a look at what it means, what the mutation has to do with various aspects of the molecules that are responsible for the binding of antibodies.
"We took a first look, the group here in our vaccine research centre, who takes this very seriously, and (they say) that when you look at the binding sites ...
"It does not appear at this point that the mutation that has been identified in the minks is going to have an impact on vaccines and the effect of vaccine-induced immune response.
"It might have an impact on a certain (number) of the monoclonal antibodies that are developed against the virus - we don't know that yet.
"But at first cut it doesn't look like something that's going to be a really big problem for the vaccines that are currently being used to induce an immune response."
Additional reporting PA
