A more contagious variant of the coronavirus has been identified in the UK by British authorities, causing the country to be isolated internationally.

Unprecedented situation or not, dangerousness of this mutant strain, presence or not in France, efficacy of vaccines ... Europe 1 takes stock of the questions that arise on Monday.

The UK found itself isolated from the rest of the world on Monday after decisions by many countries, including France, to halt flights from UK airports following the announcement by the country's authorities of l identification of a mutant strain of the coronavirus.

Faced with this so-called much more contagious strain, the British government urgently decided to reconfine London and the south-east of the country.

While many questions are being asked about the seriousness of the appearance of this new strain, Europe 1 takes stock.

>> LIVE - Coronavirus: follow the evolution of the situation Monday, December 21

Is this an unprecedented situation?

The appearance of variants of the coronavirus is a normal process, because in order to spread, viruses generally make copies of themselves.

Several hundred variants of the coronavirus have already been identified throughout the world.

"We are not really shifting into something else, but we have an evolution which was more or less inevitable", observes the doctor and geneticist Axel Kahn, Monday evening on Europe 1. "As long as the virus circulates at a high level, there will be changes (...) which will give it an advantage. "

And the more widely the virus spreads, the more there is a risk of finding problematic variants.

This is what worries the British authorities about the mutant strain in question.

This appears to make the virus 70% more contagious.

It is this strong increase in contagiousness that is the subject of all attention, because "at the beginning of the year 2020, a mutant which responds to the sweet name of D614G had [already] replaced the Chinese mutant in the world whole and it was a little more infectious ", underlines Axel Kahn.

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Is this variant more dangerous?

For Axel Kahn, on the other hand, there is "no reason to believe" that this variant of the coronavirus is more dangerous.

For the moment, it does not seem to lead to a more serious illness, nor more hospitalizations.

The efficiency of PCR tests has not been called into question by this variant either.

But for Axel Kahn, its appearance is not for all that "good news", because "viral circulation facilitates the appearance of mutants which are even more infectious".

Does the variant call into question the effectiveness of the vaccine?

On Monday, the European medicines regulator said there was "no evidence" to suggest that the Pfizer-BioNTech vaccine would not protect against this new strain of the coronavirus.

"We have every reason to think that vaccination will also be effective against these mutants", insists Axel Kahn at the microphone of Europe 1. Even if the ineffectiveness of currently developed vaccines would be proven, the latter "can change quickly" indicates Axel Kahn on messenger RNA vaccines.

>> Find Europe Soir with Julian Bugier in replay and podcast here

Is this variant already circulating in France?

Monday morning on Europe 1, the Minister of Health Olivier Véran indicated that it was quite possible that the variant of the virus identified in the United Kingdom is already circulating in France.

But there is no evidence of this circulation at this point.

This variant was not among the 500 viral strains genetically analyzed in recent days, according to the World Health Organization.

In any case, the variant in question has already been spotted outside the United Kingdom, in Italy, Denmark, the Netherlands and Australia in particular.