More than four and a half years after its appearance in China, Sars-CoV-2 continues to circulate thanks to incessant mutations. The latest ones are the cause of a strong rebound of the virus in several European countries, including France. With effects that most often remain benign.
It has been here, it will come again… Like the ferret in the famous nursery rhyme, Covid seems to emerge and resurface where we least expect it, or no longer – wrongly, in both cases. Since the very end of 2023, however, the circulation of the virus had fallen sharply in France, reaching a minimum threshold, close to zero, at the beginning of spring. This low plateau continued for a few weeks, and unfortunately: it has been a month now that the curve has started a new (clear) rise.
The extent of the surge remains difficult to pin down precisely. “People test themselves much less than before, the photography is necessarily blurry and approximate, and the interpretation complicated,” underlines Antoine Flahault, professor at the University of Geneva.
The latest weekly bulletin from Santé publique France, published this Wednesday, June 26, nevertheless reveals some strong trends. For the period from June 17 to 23, the agency observes that “all indicators are increasing, but at levels lower than those of the last two waves”, and mentions a “moderate impact” at this stage on the health system.
An increased presence in wastewater
In detail, the actions carried out by SOS Médecins “for suspicion of Covid-19” for example jumped from 2,023 to 2,784 in one week. 2,034 emergency room visits linked to Sars-CoV-2 were recorded between June 17 and 23, compared to 1,450 from June 10 to 16. The total hospitalizations following these consultations increased from 543 to 770 (including 603 patients over 65 years old) in the same period of time.
Another clue – “undoubtedly the most telling at the moment”, according to Antoine Flahault: the SUM’Eau network, which makes it possible to track traces of the virus in the wastewater of twelve communities in the country
shows circulation increasing by 21.6%, after a jump of 49.3% already the previous week.
Deduction from the epidemiologist: even if its height remains uncertain, “we are facing a new wave which is starting and which should last all summer”. As always, France is no exception. “All of Europe is concerned. The curves even show that some countries are “ahead”, so to speak, by a few weeks. This is the case, for example, of Ireland, Portugal or Spain,” adds Professor Flahault.
The managers are called JN.1, KP.2 and KP.3
This resurgence is directly linked to the appearance of yet another variation of Omicron – more than 2,000 have already been listed – in a form called JN.1, present in France since this winter and still largely dominant in France. national scale.
The JN.1 variant itself has generated a family nicely called FLiRT, which counts among its members the “sublineages” KP.2 and KP.3. They are the ones responsible for the reversal of trend observed within our borders and beyond. The reason?? JN.1 and its offspring are capable of circumventing the immunity conferred by currently available vaccines.
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Immune escape
“To “survive” and continue to spread, the virus needs to find people who are susceptible to it,” continues Antoine Flahault. We are now all immune to the strains that caused previous waves, either through the vaccine or a previous infection. It is therefore thanks to mutations which make it possible to thwart this residual immunity that new variants emerge and end up establishing themselves. »
This “escape” capability makes KP.2 and KP.3 mechanically “more transmissible” than their predecessors. With, however, a limit of importance: according to the epidemiologist, the fault is only “at the level of the acquisition of Covid-19, not serious forms”. In other words, even if contaminations increase, vaccines continue to offer effective protection against complications associated with Sars-CoV-2.
The persistent threat of long Covid
This reassuring observation applies at least to healthy people, for whom the latest mutations do not result in “clinical specificities known to date”, according to Antoine Flahault. “We remain with the classic flu syndrome, often associated with shortness of breath, more rarely with loss of taste and smell. »
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Beware, however, of general relaxation. “There can always be complications, mainly in very elderly people, who suffer from a lack of immunity, and in pregnant women. » Beyond these categories alone, “let’s not forget that 10 to 20% of infections, all ages and all populations combined, can lead to long Covid. It’s a bit like Russian roulette, and this can result in very debilitating persistence for some. »
Stéphane Barnoin
Dijon, Grenoble, Lille, Marseille, Nancy, Orléans, Paris, Pau, Rennes, Rouen and Toulouse.
The Olympics, a future springboard for the virus?
The resurgence of Covid-19 raises questions all the more as millions of people are preparing to flock to France, and particularly to Paris, for the Olympic and then Paralympic Games. The world’s biggest event will “certainly cause a mix of variants,” predicts Antoine Flahault. In terms of health, the epidemiologist does not fear a major impact at this stage, even if he advises “those who do not want to catch Covid to favor terraces and outdoor gatherings.” The hypothesis of an outbreak of the virus in the Olympic village, however, cannot be ruled out according to him. “Like everyone else,” he notes, “athletes test themselves less and take fewer precautions. An infection will not do much damage to these young and healthy athletes. But some could well find themselves on the mat in terms of pure performance, with an impaired state of form during competitions. »To read.
Tell me?! Better health at any age , by Antoine Flahault. Editions Robert Laffont, 352 pages, €20.90.
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