“Sequencing consists of determining in a way the genetic map of the virus”, explains Professor Bruno Lina, virologist at the Croix Rousse hospital in Lyon. “This allows us to have in real time the most recent information on the evolutionary dynamics of the virus, and in particular to identify certain lineages of the virus which have particular characteristics. Lineages are variants. ”
In the laboratory, the process takes 48 to 72 hours. Please note, all positive tests in France are not sequenced. The samples most often come either from clusters to be monitored, or from a representative selection of the population. Once analyzed, they make it possible to evaluate the progression of the variants.
Scientists question the fact that the device is still too little used in France. In Denmark, on average 70% of positive tests are sequenced. In Germany, it’s around 7%. In mid-May in France, it was only 4.7%.
Some warn about the risk of a fourth wave if we do not now increase the sequencing to track down the Indian variant. For Professor Philippe Froguel, geneticist at Lille University Hospital, it would take 10 to 15,000 sequencing per week to properly identify the variant. There are 3 to 5,000 currently.