Published on : 09/03/2021 – 00:08
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In France, since the start of the Covid-19 epidemic, researchers have been studying wastewater to determine the level of circulation of the virus. Indeed, patients reject it in their stools and the Obépine network has been created for this purpose. It is a monitoring network that has grown since it was launched almost a year ago in April 2020. Today, around 120 wastewater treatment plants are part of it. The city of Paris has also joined this scientific initiative which helps fight the epidemic.
Barely out of the sewers, where they are responsible for collecting a sample of wastewater, Julien Lefevre, team leader and his colleague, go through the disinfection box. Usually, Julien Lefevre takes samples to find out if restaurants reject grease or gas stations, hydrocarbons. Since last May, her mission has changed, but not her job.
« Sewers are full of germs, bacteria and viruses so you get used to it, explains Julien Lefevre. There we are very involved, we follow the results of the analyzes. At one point, the samples were even taken directly to Eaux de Paris. We feel useful. »
It is in fact Eau de Paris, the laboratory of the City of Paris, which is responsible for analyzing the samples according to a protocol developed by researchers from the Opébine network. They then transform this data into trend curves, a valuable indicator that generally helps to anticipate the progression of the epidemic. Because the virus is present in the stool a few days before the onset of the first symptoms and even asymptomatic people excrete it.
« This summer we were three weeks to one month ahead of the indicators in Île-de-France. The virus was circulating in people who were not asymptomatic at the time », According to Vincent Maréchal, one of the co-founders of the Obépine network. “ There we are a few days ahead of individual-centered indicators. It all depends on the epidemiological context. We do not see with the same acuity a phenomenon which increases or a phenomenon which decreases. It all depends on where the virus is circulating. If it circulates in fragile populations, there will be a good correlation. When the virus circulates in a population with few symptoms, there is a significant gain », Says this virologist.
The other advantage of the data provided by Obépine is that it is targeted. They can therefore allow local elected officials to react to an acceleration of the epidemic. This is also why the Paris town hall has chosen specific sampling points.
« These are sectors with a dense population or priority districts of the city policy “, explain to us Miguel Gillon-Ritz, Head of the Water Quality Department at the Water and Sanitation Technical Service. “ The idea is to set up health actions. We are working with our colleagues in the Health Department to potentially have more enhanced awareness-raising or screening actions. »
With the evolution of the epidemic, Obepine’s missions have changed. Today, researchers are obviously focusing on variants. Once the vaccination campaign is well advanced, they will examine the residual circulation of the virus and possible resistance to the vaccines.
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