Home » a viral load 1,260 times higher, what is its circulation in France?

a viral load 1,260 times higher, what is its circulation in France?

by archyw

INDIAN VARIANT. According to further analysis of the Delta variant, an infected person would be contagious two days earlier than with the original strain. The latest update on the circulation of the Delta variant in France.

[Mis à jour le 20 juillet 2021 à 16h25] According to a new study conducted by the Chinese Center for Disease Control and Prevention, the Delta variant has a faster spread. Indeed, according to the latter, people would be contagious two days earlier compared to the original strain. To reach this conclusion, the researchers followed 167 people infected with the virus from the same person, patient zero of the Delta variant in China, detected on May 21. After performing PCR tests every day, the researchers found that it only took an average of four days with the Delta variant, compared to six during the 2020 outbreak, to infect other people.

According to Sandrine Sarrazin, Inserm researcher at the Marseille-Luminy immunology center cited by Le Parisien, “we are probably more contagious and earlier because the virus multiplies faster and the quantity of virus in the nose is much higher” . According to the same study, the viral load of Delta is 1,260 times greater than that of the first strain. In France, the incidence rate of the coronavirus has more than doubled in one week, reaching 74.6 cases per 100,000 inhabitants according to the latest figures. An increase assessed by government spokesman Gabriel Attal at 125%, who estimates that the Delta variant now represents 80% of positive cases. According to the latest data from Public Health France for the week of July 10 to 16, the Delta variant indeed represented 79.3% of the positive PCR tests screened. Here is the latest data on the progression of the variant in the country.

Three data series can be mentioned to measure the progression of the Delta variant in France. First, according to all latest data published by Public health France on its site and covering the week of the week of July 10 to July 16, 2021, 19,422 positive results for the L452R mutation, linked to the Delta variant, were recorded out of 26,966 screening results captured, or 79.3% of PCRs screened. At the same time, there were 1658 positive results for the E484K mutation (linked to the South African and Brazilian variants), or 6.8% of the PCRs screened and 319 positive results for the E484Q (marginal) mutation, or 1.3% positive tests *.

In his weekly epidemiological assessment, published every Thursday evening but exceptionally unveiled on Friday July 16, Public Health France also figures the L452R mutation at 63% of the positive samples screened in week 27, i.e. from July 5 to 11, 2021 this time. “The Delta variant has become the majority in the metropolitan area: the L452R mutation (scope
mainly by the variant Delta) was found in 63% of the positive samples screened (43% in S26) “, write the authors of the report.

Finally, we can cite the so-called “Flash” surveys once again carried out by Public Health France as part of the national genomic surveillance strategy conducted with the ANRS | Emerging Infectious Diseases (EMER-GEN consortium). The most recent, the Flash # 13 survey of June 29, indicates that the Delta variant then represented 55% of the interpretable sequences (against 35% for the Flash # 12 survey on June 22). “In Overseas Territories, other variants predominate: Beta (South African) in Reunion, Gamma (Brazilian) in Guyana, Alpha (British) in the West Indies,” writes Santé publique France.

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*Attention : only around half of the tests (48%) are now screened, ie analyzed to identify a mutation. In addition, remember that since May 31, in screening tests, Public Health France does not specifically look for the type of variant (Alpha, Beta, Gamma, Delta, etc.), but three types of mutations: the E484K mutation carried in particular by the Beta and Gamma variants, the very marginal E484Q mutation and the L452R mutation carried in particular by the Delta variant. The agency believes that a large majority of tests showing the L452R mutation (at least two thirds) correspond well to the Delta variant. The Alpha variant (British) has not been systematically searched for in the tests screened since the beginning of June. It had indeed become very large majority (90%) in the spring but the proportion of positive cases has dropped considerably since. Only Flash surveys can still track him down.

Géodes published for the first time on July 1 a map presenting the screening of the L452R mutation, characteristic of the Delta variant in France. It has since been updated daily with the latest data available. Public Health France indicates that the Delta variant is distributed with “great heterogeneity” over the territory, with a strong increase in Ile-de-France, New Aquitaine and Auvergne-Rhône-Alpes.

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The Delta variant, responsible for a murderous wave at the start of 2021 in India and therefore originally called “Indian variant”, is considered a “multiple mutant”. It actually results from an encounter between the so-called Californian strain, L452R, and the South African mutation, E484K. But this Indian virus also has other mutations. E484Q and L452R allow the coronavirus to attach better to cells to spread more easily. In addition, recent studies show that L452R is more resistant to antibodies, explained in Le Figaro Professor Gautam Menon, professor of physics and biology at Ashoka University, near New Delhi.

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The Indian Ministry of Health announced, Wednesday, June 23, that it had spotted a new mutation of Covid-19, called Delta Plus, and described as “worrying”. Three states in the country have been placed under surveillance. This variant would be even more transmissible than the Delta variant. According to a study by Public Health England, the Indian variant could lead to an increase in hospitalizations. After analyzing nearly 38,000 sequences of the virus, researchers now estimate that the “Delta” variant would have a 2.61 higher risk of hospitalization, compared to the British variant.

Because of this new form, “non-essential” businesses are once again required to keep their doors closed on weekends, when, locally, the positivity rate for screening tests, on average over seven days, exceeds 5%. , or that the occupancy rate of hospital beds equipped with oxygen exceeds 40%. The Delta Plus variant would have been identified at this stage in fifty-five patients. According to the Indian Ministry of Health, this new variant is characterized by “an increased contagiousness, a stronger ability to bind to lung cell receptors and a potentially reducing effect of the monoclonal antibody response” to its presence in the body.

But for epidemiologist Chandrakant Lahariya, “the Delta Plus is not very different from the Delta and it has not mutated enough to be able to trigger a third wave so quickly in India, where the population has probably already been infected at 60 % or 70% by the coronavirus in its previous forms “.

The symptoms are those of the coronavirus. Anurag Agarwal, director of the Institute of Genomics and Integrative Biology in Delhi, explained to Le Figaro a few weeks ago that the patients also suffered “from headaches, nasal congestion, sore throat, pain. muscular”. “You see them with diarrhea, like they did in New York last year.” And to add: “And the climate being hot and dry this season, some bleed from the nose or the throat because they cough or sneeze more”.

According to Tim Spector, professor of genetic epidemiology at King’s College London, the Delta variant “looks more like a bad cold in younger populations and people don’t realize it. This means people think they have a seasonal cold, so they keep going out to party, and therefore subconsciously can spread the virus around. “

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Empirical studies show that vaccination considerably limits the circulation of the variant and its infection. According to a note from the Directorate of Research, Studies, Evaluation and Statistics (Drees) dated July 15, 2021, cases tested positive for coronavirus in France between June 28 and July 4, 2021 (all ages combined) ) affected 80% of people who had received no vaccine dose. They were 11% to have received a first dose for more than 14 days or a second dose for less than 7 days, 3% to have recently received their first injection. Overall, only 6% of positive cases were fully vaccinated. By limiting the analysis to people with symptoms, we observe that the patients who were fully vaccinated were only 4% and the proportion of unvaccinated climbed to 83% had not received any dose of vaccine). By including partially vaccinated people, we arrive at a rate of 96% among patients, a figure taken up by Olivier Véran on Thursday, July 15. La Dress nonetheless emphasizes that these statistics can reveal biases, in particular linked to the fact that the vaccinated may spontaneously have less tendency to go to be tested or to the vaccination coverage (the greater the proportion of the vaccinated population, the more it is. will also be among the positive cases).

Other studies have already been carried out abroad to try to measure the effectiveness of vaccines against the Delta variant. These include a technical report from Public Health England, dated mid-June, giving the following statistics: in the United Kingdom, since February 1, 2021, 35,521 cases of Delta variant infections have been identified in unvaccinated people , 4,094 cases in people who received a first dose of vaccine for less than 21 days, 9,461 cases in people who received a first dose of vaccine for more than 21 days, and 4,087 cases in people who received a second dose for more than 14 days. Another reassuring element: another “real-world” analysis of 14,019 cases of the Delta variant in the UK, published again by Public Health England in June 2021, found that the Pfizer and AstraZeneca vaccines were respectively effective at 96%. % and 92% against hospitalization this time. On July 8, Pfizer reaffirmed in a statement that its vaccine would ultimately be effective against the Delta variant, especially after a possible third booster dose.

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