A series of experts have said they found no clear cause for concern that a vaccine would be less effective against the cluster 5 variant of coronavirus, which has been found in Danish minks.

Denmark’s government has applied tight restrictions in North Jutland and initiated a politically fraught decision to cull every fur farm mink in the country due to concerns that a mutated form of coronavirus originating in mink could set back vaccine research.

The decisions were based on the preliminary results of testing on a variant of the mutated coronavirus known as ‘cluster 5’, conducted by the country’s national infectious disease agency State Serum Institute (SSI).

But after SSI released a paper on its research, experts have cast doubt as to whether the mutation would have any effect on vaccine efficacy, Danish media including DR and Information report.

The SSI paper details tests conducted by the institute on the variant, which has been detected in 12 confirmed cases in humans in Denmark.

Experts told Danish media that the report did not give them initial cause for serious alarm.

“The data that have been released do not support (the claim) that this is a risk for vaccines not working,” Jen Lundgren, professor of the infectious disease department at Copenhagen’s Rigshospitalet, told DR.

A similar assessment was made by virology professor Søren Riis Paludan of Aarhus University.

“Based on the data they get, I don’t think you can conclude – and almost not even speculate – that this could be the breeding ground of a new pandemic or that the vaccines won’t work,” Paludan told DR.

Thomas Laustsen, professor of Immunology and Microbiology at the University of Copenhagen said there was no conclusive evidence in the paper of a dangerous mutation.

“With the data SSI has released, it’s very difficult to say whether this is a very dangerous mutation. We don’t actually know whether we have a problem,” Laustsen told the broadcaster.

“I can understand that eyebrows were raised when you could see in the laboratory that antibodies didn’t work as well on this mutation. But with the data I’ve seen now, there’s nothing here that makes me tremendously worried,” he added.

A fourth expert also told DR that he was not concerned over vaccine effectiveness, after having consulted the SSI paper.

“I don’t think, based on this paper, that you can say future vaccines would be ineffective or have reduced function with regard to the cluster 5 variant,” Aarhus University Hospital professor and senior consultant doctor Lars Østergaard said.

Although less sensitive than other variants, the cluster 5 variant remains sensitive to antibodies, Lundgren said to DR.

That appears to be in some contrast with an explanation previously given by SSI officials.

Five different mink-specific variants of mutated coronavirus have been discovered, of which one – ‘cluster 5' – showed a change in spike proteins on the virus.

This gave rise to concerns relating to vaccine efficacy because many of the vaccines in development are targeted towards the spike proteins on the regular coronavirus.

“What we could see was that this variant showed less sensitivity to… neutralising antibodies from recovered patients,” Tyra Grove Krause, SSI’s head of department for infectious disease epidemiology and prevention, said at a briefing last week.

“This is a concern because this may mean that in the future that some of the Covid-19 spike-directed vaccines may be less effective against this variant of the virus,” she said.

“This is not certain. We still need to do ongoing tests and research, but it's a concern,” she noted.

But the cluster 5 variant does in fact react to high levels of antibodies, according to Lundgren’s comments to DR.

“It depends on the level you expose the virus to with these antibodies; if there are very few antibodies there might be a problem, but if there are relatively many antibodies the possible problem is cancelled out, and that’s what vaccines are meant to do. They are meant to deliver many antibodies,” he said.

“These data do not support this being a threat to the vaccines,” he added.