The “old” variant of the coronavirus is regressing, but the British continue to progress. Based on the latest scenarios developed by Inserm researchers, the British variant could become dominant in France during the last week of February or the first week of March. Their results, posted on February 14 on the platform Epicx-lab, confirm their previous estimates.

A fragile balance

For this new study, the researchers used updated mathematical models thanks to the results of the first Flash survey on the circulation of the British variant.

First point that these models make it possible to understand: the stabilization of hospitalizations currently observed results from a balance between two opposing dynamics. On the one hand, the decline of the “old” strain with an effective reproduction rate R lower than 1. And on the other hand, the rapid growth of the British variant.

Which leads to a second point: this balance should not last long. Because the British variant continues to gain ground and should therefore tip the balance towards an increase in the number of contaminations, hospitalizations and deaths.

Read also: Covid: why the new variants could lead to more deaths

The dominant English variant by early March

The curves should therefore start to rise again, but when? As soon as the British variant becomes the majority, that is to say, it will represent more than 50% of contaminations. At the national level, this threshold should be crossed “late February – early March“, according to the researchers.

Currently, according to the latest data from Cerba laboratories – leader in the sector which has around 500 medical analysis laboratories in France – out of 4,000 screenings carried out per day in the country, the analyzes find “on average 35% of English variant“explained on February 15 its CEO Sylvie Cado at the microphone of franceinfo.

Four more affected regions

But locally, the numbers are higher. In Île-de-France in particular, Inserm foresees an increase in the British variant in mid-February.
What Sylvie Cado confirms. Its Ile-de-France laboratories account for 40 to 45% of cases due to British variants. Other regions show higher rates than the national average, namely the Provence-Alpes-Côte-D’azur, Nouvelle-Aquitaine and Hauts-de-France regions.

“Save time” before a new peak?

What to expect, according to these specialists? “In the absence of strengthened control measures, rapid growth of cases is expected in the coming weeks“warn Inserm researchers.

Several factors could nevertheless help “save time before the resurgence of cases “:”the additional measures taken on January 31, a possible slowdown induced by the winter school holidays and a strengthening of the test-trace-isolate strategy. “

As for vaccination, it constitutes an effective means of fight but its impact should not be felt before April, warn the researchers.