It poses the threat of a fourth epidemic wave after the summer. In one month, the Delta variant has spread at high speed, although its geographical distribution is very heterogeneous. At the same time, the Alpha variant, from the United Kingdom, continues to decline. It is therefore likely that it is no longer the majority in France, in favor of the Indian strain, estimated 40% more transmissible. Thursday July 1, Public Health France published new indicators on the Géodes platform. They reveal the prevalence of three mutations, including L452R, notably present in the Delta variant.
And these first results confirm the rapid progression of the Indian strain, which has already become the majority across the Channel. As of June 28, 25.8% of positive Sars-CoV-2 tests screened would be linked to infections with a strain carrying the L452R mutation. As a reminder, screening is a technique which makes it possible, from a positive test, to suspect an infection by a viral strain, or by a mutation of the virus. The first results of the screened tests, however, attest to a very heterogeneous circulation of the mutation: 81.4% in the Landes, 38.7% in Paris, 5.3% in the Ardennes. Even if the L452R mutation has been identified in five viral strains of Sars-CoV-2, a very large majority of these prevalences would be linked to the Delta variant, which is for the moment the only one among the five variants carrying the L452R mutation, classified by the World Health Organization (WHO) as VOC, i.e. as a variant of concern.
3 mutations tracked down by health authorities
In order to refine the surveillance of the epidemic in France, Public Health France has revised its strategy to no longer target the Alpha (English), Beta (South African) or Gamma (Brazilian) variants and now actively track three mutations , common to different variants classified as of concern (VOC) or of interest (VOI): E484K, E484Q and L452R. For example, the E484K mutation, which was found in 23% of the positive tests that were screened as of June 28, is carried by the Beta and Gamma variants. And it was even acquired by the variant “B.1.1.7”, the code name for the British variant, just like the E484Q mutation, spotted in 0.7% of the positive tests screened in France.
For now, it is the L452R mutation that is attracting the most attention from epidemiologists and authorities, given the rapid progression of the Delta variant. As of June 29, according to the latest weekly epidemiological score from Public Health France, the three regions which have recorded the most positive cases linked to this strain of Sars-CoV-2 are Nouvelle-Aquitaine (111), Île-de -France (82) and Provence-Alpes-Côte d’Azur (63). And all regions have reported at least one case of Delta variant infection.