The Covid epidemic after the end of the mask, according to the Pasteur Institute

CORONAVIRUS – “You have to relax: it is going up everywhere, but hospital capacities are no longer overloaded and everyone is getting vaccinated.” This is what’s slipping this Thursday, March 10 at HuffPost a government heavyweight on the future of the Covid-19 epidemic, in a context where the contamination in France is starting to increase slightly again. A weighing report accredited by the modeling published at the same time by the Institut Pasteur.

Indeed, modeller Simon Cauchemez’s team is revealing new hypotheses about the evolution of the coronavirus just before the cut of health measures on March 14; the mask will only be required in a small number of cases. And good news: regardless of the size of the discharge, the researchers foresee a peak in contamination that is much lower than last January.

A 6th wave with no common measure with January’s

So whether the French relax their vigilance on March 14, as the authorities will allow, or a week earlier, the models of the Institut Pasteur do not foresee an explosion in the number of cases comparable to that at the beginning of the year. At that time, at the end of January, an average of more than 300,000 daily cases had been detected in a week.

The, as you can see in the graphs below, in the worst case (in purple) the maximum number of new daily cases would not exceed 170,000. And again, this would be in an extreme case, where Covid transmission would increase by 130% compared to the January-February period (when the measures were stricter).

As a reminder, Pasteur notes that last November, when control measures were particularly lax, transmission rates were “only” 60 to 70% higher than in January-February. The most extreme hypothesis for the coming weeks is therefore very pessimistic and the reality could be lower.

How long for immunity?

But these predictions are far from trivial. They show that the immunity granted by Omicron and the mechanical vaccination make it possible to limit the future size of the epidemic, even in the event of a significant relaxation of barrier movements and sanitation measures.

This is what the researchers have observed since February 22, the date when they observe a first easing of behavior in light of Covid, particularly in connection with school holidays. As you can see below, thus, according to the hypotheses, they detect a plateau or even a limited rebound. Observations that make it possible to imagine a sixth wave, if indeed it does occur, with no common measure with the fifth.

However, a great unknown remains: how long does the immunity conferred by infection with Omicron last? This – and the weather that should logically be much more lenient in the spring – will also depend on the future of the epidemic. And it is because they have few elements on the subject that the researchers at the Institut Pasteur for the time being refuse to plan after April 1.

Rest and vigilance

However, if they have no idea about a particularly short-term immunity, it is impossible to rule out this possibility. What makes them say, “To make long-term projections, it will be important to consider the decline in immunity and the effect of climate on epidemic dynamics.” To be continued.

In addition, as Simon Cauchemez’s team had predicted in mid-February, the BA.2 variant, Omicron’s “little brother” with very similar characteristics, has continued to evolve relative to the infestations. But, as the researchers also felt, it did not trigger another massive wave of contamination.

Nevertheless, the minister quoted above calls for not to declare victory too quickly. “We must remain vigilant. Every time we announce an easing in a calm situation, things go up. A contingency for which the health system is nevertheless ready to cope is assured to us. “It’s not because it goes up that there will be a strong impact on our health capabilities.”

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