Half of the coronaviruses detected. This is the proportion occupied by the British variant in wastewater from Île-de-France, according to information from France Blue Paris. This figure comes from Obépine network, the epidemiological observatory of wastewater. Their analyzes of water from wastewater treatment plants make it possible to locally monitor the evolution of the covid epidemic and that of the various variants.

No local disparity

Since the British variant was spotted in the wastewater of Île-de-France in January 2021, its proportion has continued to increase. Today, it thus represents 50% of coronaviruses “throughout the Ile-de-France region, with no notable difference depending on the area“, explains to France Blue Paris Laurent Moulin, Research and Development manager at the Eau de Paris laboratory.

To read also: Why the study of wastewater made it possible to avoid a new reconfinement

Spot a “trend”

What does this number mean? It does not reflect a strict reality and therefore does not mean that one in two patients is a carrier of the British variant. But he describes “a trend, an idea of ​​the evolution of the epidemic“notes Laurent Moulin.

It is these trends, upward or downward, that researchers from the Obépine network have been tracking for several months. Extremely valuable data because even people with few or no symptoms can excrete traces of the virus in their stool, which then ends up in wastewater systems.

This allows specialists to spot any resumption of an epidemic early and to alert locally, even before the numbers of positive cases or hospitalizations increase.

Concurring figures

Their data on variants will also be of great help to better understand their propagation. And for now, the figures for wastewater are consistent with those of screening tests, which make it possible to count the number of people contaminated by the variants among those who carry out a PCR test. In fact, in mid-February, the Cerba laboratories located in Île-de-France had between 40 and 45% of cases due to the British variant.

And for his part, Inserm predicted that this variant would become dominant, that is to say that it represents more than 50% of covid cases, at the beginning of March in the Île-de-France region.