The delta variant was the unpleasant surprise of spring : at least twice as contagious as the original strain, it has caused a restart of the covid-19 epidemic, partially controlled, in France, by the progression of vaccination. Does Sars-CoV-2 have new cocktails of mutations in store for us? in the coming weeks ? Which, in the worst case, would give it even greater contagiousness and dangerousness? The President of the Scientific Council, Jean-François Delfraissy, clearly announced in an interview on BFMTV, a few days ago: “We will probably have another variant which will arrive during the winter”. In question, “the extraordinary mutation capacities” of this coronavirus.
In winter, or maybe even before. A study published Friday in the journal Nature Scientific Reports shows that the moment we are living in today is propitious for the emergence of variants resistant to immunity acquired naturally or by vaccines. The authors of this work first establish that rapid vaccination reduces the risk of the emergence of such variants. But they specify that “counterintuitively, the probability of emergence of a resistant strain is greatly increased at a time when most individuals of the population have already been vaccinated and when a relaxation of non-pharmaceutical interventions (gestures barriers, wearing a mask, etc., Editor’s note) occurs ”.
The vaccination threshold from which the risk becomes high is 60% of the population, which is the percentage that France should reach in the next few days. The so-called “selection pressure” phenomenon could then increase: the virus still circulates a lot, particularly among the unvaccinated, and the more the population will develop antibodies, the more the strains which are resistant to it will benefit from it. The scientists conclude that “policymakers and individuals should consider maintaining non-pharmaceutical interventions and transmission reduction behaviors.” And this until the end of the vaccination campaign and acquisition of group immunity, estimated at around 85% for the delta variant.
The mask worn less systematically
Problem, a clear relaxation of barrier gestures is observed among the French in this month of July, reveals the Coviprev study by Public Health France. She has questioned 2,000 people on these questions since March 2020. Between July 15 and 21, they were only 68.12% to wear the mask systematically in public against more than 80% in mid-May. Still in mid-July, the French who said “greet without shaking hands and avoiding hugs” now represented only 62.5% of the population, ten points less than two months previously. Among those reluctant to take preventive measures: “Most often men, young people aged 18 to 34 and those with a low level of health knowledge,” says Public Health France.
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