The best strategy to prevent the spread of COVID-19 in business, school or high school is to maintain a rotation between the two groups, one comes on site and the other stays at home, a French study shows.
The authors from several research institutes, including CNRS, INRIA and the University of Paris, have sought to determine which measure is most effective in “stopping the spread of infection in society positively from the first case”.
For the three areas studied (company, elementary school and high school preparatory class), the result was the same: “From best to worst: weekly rotation, daily rotation, weekly alternation and daily alternation”, plus the study published in the journal Computational Biology.
An alternative strategy that prioritizes maintaining coordination between employees and students involves everyone going to the office or class at once, then staying home at the same time.
The rotation divides the group into two: Group A goes there before reversing when Group B is at home.
This “hybrid” system was set up as part of French colleges and high schools last academic year, and for now, if the health situation deteriorates, the start of the academic year may return “face-to-face”. To all students.
“Prevent the Outbreak”
The model developed by the researchers mimics the interactions between individuals, but the “behavior” of the Sars-CoV-2 virus is due to the presence of “superpropagators”, which, if infected, infect more people than average, making them more likely to become infected before symptoms appear.
In the case of primary school, when no action is taken, they estimate that a positive case leads to an epidemic focus (minus five defined in other infected individuals) with more than one risk in one (27.3%).
This ratio drops to 17.3% with daily rotation, 16.6% with weekly rotation, 12.3% with weekly rotation and 12% with weekly rotation.
Similarly, weekly rotation is the most effective device to prolong the time before the first case leads to infection focus and before reducing the total number of infected people.
However, these strategies only work if virus transmission is still limited.
Therefore, in the case of high school, if the local reproduction rate of the virus is greater than 1.7 before taking action (i.e. contaminating an average of 1.7 each time an infected area is infected), “none of these strategies are complete- time is enough to prevent the focus of infection”.
On the other hand, with a reproduction rate between 1 and 1.38, four strategies make it possible to bring it below 1, which indicates the boundary between infection growth and regression.