COVID-19: Should we fear waves every six months?

The emergence of subvariants can occur every six months. (© Liberty Caen)

While this Monday, May 16, 2022, in France, marks the end of the mask obligation on public transport, if we fear The epidemic will resume in the coming weeks or months ?

A question arises, especially when it appears Sub variants of Omicron, BA.4 and BA.5raises fears of a fifth wave in South Africa, where Omicron has already left at the end of 2021.

These variants, which can be more contagious but not more virulent, according to South African researchers, have already been identified in more than a dozen countries, mainly in Europe, and Two cases have been identified in Franceaccording to Public Health France.

Does the arrival of these sub-variables mean the departure of a wave every six months from now on? Here are the assumptions.

Towards a new wave in Europe?

According to studies recently published in the journal temper naturedevoted to the emergence of BA.4 and BA.5, these two Omicron subvariants can “bypass some of the immune protection conferred by previous infection and vaccination.”

What indicates an epidemic rebound in Europe? As it was expressed at the beginning of May in France information The president of the Scientific Council, Jean-François Delfraissy, said, “The BA.2 wave will end at the end of May, and it will drop to low numbers, i.e. about 5,000 to 10,000 new infections per day (compared to approximately 23,000 cases as of Sunday, May 15, 2022).

But the head of the scientific council noted that “that was the level we were at last year, and everyone was very reassured also in May, and unfortunately the Delta version arrived at the beginning of June.”

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In this context, even while remaining “reasonably optimistic about the coming weeks and months for France and Europe,” Jean-François Delfraissy acknowledged:

We can expect a new variable to appear, which we value instead at the beginning of the school year, but if it does, it will arrive sooner.

Jean Francois DelfraissyHead of the Scientific Council

New wave weaker?

There is no new variable this time, but sub-variables. According to the South African researchers, while Omicron sublines appear to be more contagious, these subvariants are “not likely to cause significantly more serious disease, especially in vaccinated individuals.”

Classified as variables to be monitored by the European Center for Disease Prevention and Control (ECDC), these two subvariables could lead to “a significant overall increase in Covid-19 cases in the European Union in the coming weeks and months,” according to the organization. , which fears a rise in hospitalizations, has already seen an increase in BA.5 cases in Portugal for several weeks, as “BA.5 will become the dominant variant in Portugal by May 22, 2022” according to ECDC estimates.

If this scenario happens on a larger scale, However, there is really nothing to worry about Currently according to researchers from South Africa, mainly due, in Europe, to the vaccination coverage rate and immunity acquired during previous waves.

“It gives hope that in Europe it may have less advantage and cause a smaller wave,” he expressed in temper nature Tom Winsellers, biologist at the Catholic University of Louvain (Belgium).

Have we reached the endemic stage?

In any case, with the emergence of these new sub-variables, the South African researchers are working to strengthen their hypothesis that the evolution of the Covid-19 pandemic is gradually approaching. endemic form. Without really disappearing from the scene, the virus would still be around, with infections re-emerging at certain times, depending on the arrival of new sub-variables. Kind of like the flu.

In this scenario, immune-damaging mutations in circulating variants, such as Omicron, could combine with reduced population immunity to become major drivers of periodic waves of infection.

Nature review

But what is the difference between endemic and epidemic? a Epidemic It is an epidemic that exists in a large international geographic area, while we are talking about it endemic To indicate the presence of a disease in a particular area.

A wave every six months?

According to the researchers, The emergence of new sub-variables appears to occur approximately every six months. He said in “Maybe that’s what we should expect to see more and more in the future” temper nature Benny Moore, a virologist at the University of the Witwatersrand in Johannesburg (South Africa).

“The further we go, the more we get the impression that we are moving towards this kind of scenario, as we François Bricker, former head of the department of infectious and tropical diseases at Pitié-Salpêtrière Hospital. Where we previously observed an epidemic in acute phases, with waves, things have become more chronic.”

This is also what the Directorate General of Health (DGS) has already made clear At the beginning of the year, he estimated that “the decline over the past two years indicates that the virus is endemic, with successive waves, possibly accompanied by seasonality.”

But will the virus allow us to spend the summer in peace until the beginning of the school year in September? Answer in the next few weeks.

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