Is the eighth wave of Covid-19 slowing down? In any case, this is what the indicators of the epidemic seem to show. As the incidence rate, which “stabilized at a nationally high level after five weeks of increases.” This reference indicator for monitoring the evolution of the epidemic reported 567 cases per 100,000 inhabitants on October 17, according to the weekly bulletin published on Thursday, October 20, by Public Health France. A certainly high figure but which stabilized before beginning to decline in recent days.
If it seems that the peak of contagion has been reached (more than 53,000 daily cases on average in the last seven days), this eighth wave of the coronavirus nevertheless continues to send thousands of patients to the hospital (6,556 new hospitalizations the week of October 10 ). ) and in intensive care (8% more than the previous week). And Covid-19 continues to kill hundreds of people every week: 390 patients died the week of October 10, 23% more than the previous week. What are the lessons to be learned from this fall wave? Franceinfo takes stock with epidemiologists.
The peak of contamination coincides with the start of the school year
We note, in the graph below, that the incidence rate of the Covid-19 epidemic started to increase again at the beginning of September. “The correlation is perfect with the start of the school year.points out the epidemiologist William Dab, contacted by franceinfo. We saw the wave restart just a few days later.” The former Director General of Health cites several examples of measures that have not been sufficiently implemented to stop this eighth wave: ventilation systems in closed places, at work or at school, or even the obligation to wear a mask in transport and closed places. .
The rate of change in the number of contaminations since the beginning of September confirms the observation made by William Dab. There is clearly a sharp increase in cases (represented in red in the graph below) from the week following the start of the school year, which took place on September 1. “This is the result of an epidemic recovery mainly due to Omicron BA.5”, explains to franceinfo Mircea Sofonea, epidemiologist at the University of Montpellier. And this, due to two phenomena that reinforce the risk of contamination: “the immune impairment and the fall season”. “AWith shorter and cooler days, the population increases its stay in closed spaces, where transmission is favored”explains the specialist.
This back-to-school wave could well end during the All Saints holidays, which begin on Saturday, October 22 for the entire country. They have “in the past, it slowed down the circulation of Sars-CoV-2”Mircea Sophonea says. But we must not declare victory too quickly. An increase in cases could follow due to “school resumption, the spread of BQ.1.1 [un nouveau variant qui émerge en Europe] and the beginning of the winter season”warns the epidemiologist.
The main lesson of this eighth wave is also good news: the number of hospitalizations during the period was “among the weakest” compared to previous waves, says Mircea Sofonea. In “special” regarding intensive care admissions. A drop attributed to the vaccination coverage rate, which was, on October 17, 82.5% among people aged 65 and over, according to Public Health France. This lower number of hospitalizations “It is a sign that vaccination protects well against severe forms in the long term”highlights Mircea Sophonea.
In addition to the vaccination rate, it is the spread of the Omicron variant that explains this low number of hospitalizations. “This is unprecedented in epidemiology: at least 70% of people have an Omicron infection. But we must not believe that it is over.”warns William Dab. “Many large-scale studies have shown that the more infectious episodes we have with this virus, the more our thread of complications increases. In particular, diabetes, heart attack and stroke”, underlines the epidemiologist. According to him, therefore, we must get rid of the idea that Covid-19 is no longer dangerous because it would send fewer people to hospital immediately. “This virus will leave traces in the medium and long term. The more we can avoid contaminating ourselves, the better.says William Dab.
Less severely affected children
Other good news, on the children’s side: this eighth wave, caused mainly by the BA.5 sublineage of Omicron, has resulted in very few Pims, these pediatric multi-system inflammatory syndromes that affect certain children with Covid-19. “Five cases have occurred since the beginning of August”points out Public Health France, in its bulletin published on October 20.
This sharp decrease in the risk of Pims “could be explained in particular by a lower capacity ofOmicron to trigger hyperinflammation“noted the authors of the American scientific journal Jam Pediatricsquoted in the parisian. Another hypothesis: that the pims “occur especially after a primary infection”advances to the newspaper Christelle Gras Le Guen, president of the French Society of Pediatrics (SFP).
“In recent weeks, the evolution of the epidemiological situation in children under 18 years of age has been characterized by a decrease in incidence rates”, confirms for its part Public Health France. The number of pediatric hospitalizations for Covid-19 has remained stable for a month. In most cases, children under 1 year of age are hospitalized. The week of October 10, these young children accounted for 59% of hospitalizations for children ages 0-17 and 48% of intensive care admissions.
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