has the virus circulating in France mutated?

For several weeks, France has registered an increased contamination with Covid-19 without the situation deteriorating for all this in hospitals. Decryption with Patrick Berche, professor of microbiology in Paris.

Are we in France heading for a second epidemic wave as strong as the first? Although the indicators for several weeks have shown an increased circulation of the new coronavirus in France, the number of hospital admissions and admissions to intensive care remains stable.

In total, more than 4,500 new positive cases of coronavirus were detected daily Thursday and Friday, figures published since May, according to Public Health France. This indicator has risen steadily for several weeks (+ 43% last week, + 39% the previous one), while the screening rate is “stable”, states the health institute, which reports in its latest bulletin. a doubling of cases every 17 days.

Other markers of the “strong development of the circulation of the virus”, the number of new focuses on grouped cases (“clusters”) is increasing “still” and the rate of reproduction (called “R”) is about 1, 3 since the end of July. The latter figure indicates the average number of people infected with each carrier of the virus. When it is above “1”, the epidemic develops.

For microbiologist Patrick Berche, former head of the Institut Pasteur de Lille, interviewed by France 24, “there is a difference between the number of cases detected and the number of people admitted, which remains stable”.

Hypotheses but no guarantees

The specialist puts forward two hypotheses to explain this discrepancy: “Either the number of people affected, especially people between the ages of 20 and 60 and people at risk, is more protective,” explains Patrick Berche. “Either the virus loses its virulence. A mutant [du Covid-19], D614G, is believed to circulate in Europe and the United States and is less virulent and more contagious. It is currently predominant over other strains of coronavirus. “

Covid-19: “there is a mismatch between the number of cases detected and the situation in hospitals”

“During epidemics, viruses tend to lose their virulence. Is this the case? That would be good news,” he said.

An article recently published in the journal Cell has really revived the hypothesis of a mutation of the virus that would have made it more contagious but less deadly. But other specialists point out that this strain of the virus that carries the mutation has been identified since April and was already circulating in Europe during the first wave. They therefore consider that it is hardly credible that it is the cause of the lower mortality rate that is currently being observed.

“We are at a crossroads, we may have an epidemic that will continue very slowly or we may have a second wave with the return of a cold and wet season that would lead to a greater spread of the virus,” continues Patrick Berche. who prefer to be careful in the absence of convincing studies.

A matter of time

“The situation is worrying,” said Judge Renaud Piarroux, head of the Pitié-Salpêtrière hospital, questioned by AFP. The more the number of new cases develops, “the more need in tests, in laboratory samplers, in tracking increases”, and “the greater the risk of being in a situation where it will be difficult to identify all cases” and where we will lose control of the virus, explains infectious disease specialist.

For some physicians questioned by AFP, the spread to at-risk populations (elderly or who have a fragility factor such as diabetes or obesity) of the increased circulation of the virus is only a matter of time. .

“An increase” in the proportion of new cases, although less strong than in other age groups, has already been “observed in people over the age of 65”, emphasizes Public Health France. And although the numbers in hospitals have nothing to do with what they were in the spring, there is a “rising trend in new hospital admissions and intensive care admissions”.

On Thursday, French President Emmanuel Macron estimated that there were “reasonable chances” of getting a vaccine against the new coronavirus “in the coming months”. “For an epidemic to end, a large number of people must have been in contact with the virus and produced antibodies to protect against it,” explains Patrick Berche. “The vaccine can help achieve this herd immunity.”

With AFP