Second wave seeks guilty.

While European countries are implementing, one after the other, increasingly strict measures to fight against the spread of Covid-19, many epidemiological questions remain open about this second wave.

While most scientists have admitted to having been surprised by the speed at which the virus has spread since the end of the summer, a little more is known about how the virus has spread on the continent.

A mutation of Sars-cov-2, which appeared in Spain in early June, has established itself as the dominant form of the virus in at least a dozen countries, an international team of scientists determined in a new study released Thursday, October 30.

Storming Europe from July

It was in early June that the 20A EU.1 strain - the name these researchers gave it - seemed to have emerged among agricultural workers in the Aragon region in northeastern Spain.

“It is at least the oldest traces of its presence that we have been able to detect”, specifies Emma Hodcroft, the main author of the study and specialist in human evolutionary genetics at the University of Basel, contacted by France 24. 

It then mingled with the local population before migrating to the rest of the country where it now represents more than 70% of all the sequences analyzed by the researchers.

From mid-July, this mutation quickly took the rest of the continent by storm, starting with the United Kingdom (80% of all sequences analyzed), Switzerland and the Netherlands.

In France, "it represents only 40% of the cases analyzed, and it is another strain which is dominant", specifies Emma Hodcroft.

"I had never met a strain of virus, which spreads so quickly since I studied mutations in Sars-cov-2", admits the scientist from the University of Basel.

Does this mean that Europe has fallen under the influence of a new particularly aggressive strain of the coronavirus, which could explain why scientists have been taken aback by the rapid increase in contamination since the start of the school year?

Without ruling out this possibility, Emma Hodcroft would like to point out that “at present, we do not have scientific proof that the mutations have increased the transmissibility of the 20A EU.1 variant or made it more dangerous”.

Changes in the genetic structure of a virus are frequent - they occur when the virus multiplies in an infected body - and "most of the time they do not affect the way it behaves", recalls the researcher.

But it sometimes happens that the genetic lottery gives birth to a more virulent strain.

This is the case with the D614G variant which was described as “more infectious” than the others in an article published in July in the journal Cell.

Determining whether Sars-cov-2 20A EU.1 falls into this same category will require additional laboratory testing.

The verdict should fall "in a few weeks", specifies Emma Hodcroft.

Is it the virus or the vacationers?

In the meantime, the lead author of the study considers it just as likely that the very rapid spread of this strain of the coronavirus is more prosaically a side effect of the summer holidays.

“We know that contaminations after deconfinement started to rise again very early on in Spain, a very popular destination for tourists, and this variant of the virus began to circulate at European level at the time of the great summer movements of holidaymakers”, recalls- she does.

In addition, many of these tourists are relatively young, and some of them were able to “apply barrier gestures badly” to better celebrate the return of a certain normality after a confined spring, notes the researcher.

“It was the perfect cocktail for this strain of the virus,” she says.

But for 20A EU.1 to leave the country, there must also have been "failures of health checks at airports," said the Financial Times.

This explanation has the advantage of removing the specter of a steroid form of Sars-cov-2 which would have imposed itself in Europe.

But if the fault is not genetic, the responsibility for this second wave falls on human behavior.

Which is not necessarily more reassuring.

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