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Covid-19: what we know about the Delta variant which has just been detected in Brittany – France

What are the characteristics of the Delta variant?

The Delta variant, whose scientific name is 21A / 478K, was first detected in India in October 2020. This strain took precedence over two other “cousins” spotted in this country, one of which is called variant Kappa. He was flushed out in France last April and in Brittany this week. It has a particular mutation, L452R, which is said to decrease the efficiency of the immune response by producing antibodies. And it would increase the virus’s affinity for the receptor in human cells allowing it to enter it.

Is it more contagious than other variants?

Public health France ensures that “the English epidemiological data show an increased transmissibility of this variant compared to the reference viral strains and to the Alpha variant (new name of the British variant, Editor’s note)”. To reach this conclusion, the health agency relies on several British scientific studies which assess that the potential for transmission in family homes is increased by 40 to 60%. In addition to being spread more easily, this variant would be responsible for “a probable increase in the risk of hospitalization”.

Is it more resistant to vaccination?

The efficacy of the vaccines would be slightly reduced against the Delta variant. Especially after a single dose. Public Health France nevertheless notes that after two doses, the risk of contracting an infection with symptoms is reduced by approximately 80%, whether with the Pfizer or AstraZeneca vaccine. The level of protection would also remain “very high” in the face of the risk of being hospitalized. “As it stands, the vaccines are reasonably effective against this variant, even if there is a small delay in ignition: it takes some time for protection to set in”, Alain Fischer told us, the “Monsieur Vaccin” of the government.

How fast is it spreading around the world?

The Delta variant is now present in at least 80 countries. In the United Kingdom, its progression is galloping since during the first week of June, it represented 74% of sequenced samples. Result : the incidence rate across the Channel is on the rise again : 70 per 100,000 inhabitants on June 15 against half less, 15 days earlier. In addition, the Delta variant is widely distributed in India and in neighboring countries, as well as in the United States, where it weighs almost 10% of the positive samples sequenced.

And in France ?

Flash surveys are carried out every two weeks in order to measure the progression of variants in the country. During the tenth edition, carried out on May 26, the Delta variant was only present in 1% of the positive samples studied, against 86% for the Alpha. But it is progressing clearly: this percentage was only 0.2% two weeks earlier. Its presence in the hexagonal regions is disparate. While it has just been detected in Brittany, it has already generated significant clusters in the Landes, mostly made up of young and unvaccinated people. It is particularly present in Bas-Rhin, Ile-de-France and Provence-Alpes-Côte d’Azur. A hospital cluster has also been observed in Loire-Atlantique. It is now suspected of circulating at low noise and gives rise to fear of a fourth wave from the start of the school year, “if we do not achieve collective immunity by next fall”, told us Yves Buisson, president of the covid-19 cell of the Academy of Medicine.

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