Laure Dautriche, edited by Cédric Chasseur 8:01 p.m., August 26, 2021

A few days before the start of the school year, scientists from the CNRS looked into the question of the transmission of the virus within a group.

How does an epidemic arise?

Is it possible to limit its spread?

Their conclusions shed light on the strategies to adopt, both in schools and in the workplace.

DECRYPTION

For more than 12 million young French people, back to school is approaching.

In a week, the students of metropolitan France, from kindergarten to high school, will resume the path of lessons.

But as in business, the Covid-19 may require a certain gymnastics.

A new health protocol, announced this Thursday by the Minister of National Education, Jean-Michel Blanquer, will be implemented next Thursday.

And it will sometimes be necessary to juggle face-to-face and teleworking to limit the risk of an epidemic.

What is the best organization to adopt?

About ten scientists from the CNRS have studied these questions.

They deliver their conclusions this Thursday.

Weekly turnover, the best strategy?

How to organize the best in these conditions?

Is it better to divide the classes into two: one group in the establishment, the other at home?

Is it more effective to alternate daily or weekly?

For these researchers, if cases emerge in certain places, the most effective in slowing the epidemic is one rotation per week.

The first half of the class goes to class, the other half works at home.

A more popular hypothesis than the solution of a rotation every day with everyone present or everyone absent.

"It was the best strategy", confirms Claire Mathieu, research director at CNRS.

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The computer scientist details how her team came to this conclusion.

Group A comes to work or school every other week, and group B does the opposite.

"We calculate the probability that there is a cluster in a school and we calculate the time before there is this cluster, we calculate the number of days," she explains.

Daily turnover as efficient as weekly turnover

Interestingly, the second strategy, that of daily rotation, is almost as effective as a weekly rotation, according to experts. For them, the main thing is therefore to implement one of these two techniques to make it possible, whatever happens, to prevent the virus from spreading. New elements that will undoubtedly inspire public health authorities, who may have to make new decisions in the coming weeks.