Such a level of precision had never been achieved for this type of information.
Public Health France unveiled Thursday evening, in its weekly epidemiological update, the proportions of suspected SARS-CoV-2 variants by department and by age.
These results come from the "screening" of just under half of the positive tests identified from February 8 to 14 (the goal is to achieve 100% of the tests screened as quickly as possible).
This technique makes it possible to track down the characteristic mutations of the so-called “British” variant, or of those called “South African” and “Brazilian” (categorized together because they share a common mutation, E384K).
Until then, only fragmented data had been communicated at the regional level, thanks to the various Flash surveys carried out on a sample of positive cases.
From now on, the results of the “screening” are integrated into the SI-Dep database.
They are not yet available precisely in open data by department, but Public Health France has disclosed them by percentage bracket.
On the other hand, we now have the first precise proportions of variants by age category, at the national level.
Here's what to remember.
Strong territorial disparities
Whether for the so-called "British" variant (called B 1.1.7 or 501Y.V1 in scientific jargon) or for those originating from South Africa and Brazil, the map of France shows strong disparities depending on the territories. .
At least a third of the positive tests were screened in each of them, which provides data deemed significant by Public Health France.
READ ALSO>
“English”, VOC 202012/01 or B 1.1.7… How to name the variants?
The "British" variant accounts for 37% of positive cases nationwide and is present in all regions, according to the latest results available as of February 18.
Twelve departments show a proportion of positive cases linked to this variant greater than 50%.
However, none of Ile-de-France is part of it, contrary to what one might have thought from reading the Flash surveys.
These twelve most affected territories are scattered throughout the territory.
Unsurprisingly, the North is one of them (nearly 70% of this variant is recorded among the new cases in Dunkirk).
There are also Var, Vienne, Morbihan and Aube.
“It's not necessarily a surprise, we have a large immigrant community from Great Britain in the south of the department.
On the other hand, today there is no outbreak of contaminations ”, indicates the deputy of Vienne Sacha Houlié.
The incidence has fallen sharply for a week in his department, far from being the only one faced with both a high proportion of variants and a drop in new cases.
"It does not worry me more than that at this stage since the various indicators tend to decline in recent days", echoes Paul Molac, deputy for Morbihan.
"Honesty obliges me to tell you that, for the time being, we do not know how to explain [this kind of scenario]", acknowledged Olivier Véran on this subject on Thursday evening.
Morning essentials newsletter
A tour of the news to start the day
Subscribe to the newsletterAll newsletters
For the so-called “South African” and “Brazilian” variants, ten departments show a proportion greater than 10%.
Only one of them, the Moselle, is above 40%.
Not surprisingly, since this border department of Germany and Luxembourg had been explicitly presented as being the most worrying by Olivier Véran on Thursday 11 February.
It is also the Academy of Nancy-Metz which concentrates the largest number of schools closed because of Covid-19 this week (24 out of 66), according to the situation of the Ministry of 'National Education posted online this Friday morning.
However, the health protocol provides in particular for the closure of the class if a student has been contaminated by one of these two variants or if he is a risk contact with a loved one in this case.
Children most affected by the English variant
The analysis of the proportion of variants by age group at the national level highlights children and young people as the most affected categories.
This is especially the case for the “British” variant.
The proportion is highest among 0-9 year olds (45.1%), ahead of 30-39 year olds (41.6%) and 10-19 year olds (40.9%).
These rates may raise fears that this variant "attacks" children more easily, recalling the alert launched by a nurse in London at the end of December.
But the pediatric pundits across the Channel immediately denied any increase in hospitalizations of the youngest.
READ ALSO>
Covid-19: are there really many more children hospitalized in England?
"A priori, there is no particular tropism of this variant towards the youngest populations", indicated this Friday afternoon during a remote press point Bruno Coignard, director of the infectious diseases department of Health public France.
According to him, the main hypothesis at this stage is linked to the fact that children have more social contact than other categories of the population, especially since schools have remained open.
"The elderly certainly have a stronger propensity to protect themselves, with fewer opportunities for contact," he added.
People over 70 appear to be much less affected, with a proportion of “British” varying between 20 and 28% depending on the age group.
The same goes for the “South African” or “Brazilian” variants, where the proportions are much lower than the average in very old people.
This point of view is shared by the microbiologist Patrick Berche, member of the Academy of Medicine.
“Children can be just as infected, but they are probably less contagious, especially because they have fewer symptomatic forms.
I am not surprised that the highest proportion of variant English are at home because they have a lot of contacts, especially at school.
Consequently, the virus can spread more strongly, ”he tells us.
Experts from Public Health France will nevertheless look into the subject in order to confirm this hypothesis or put forward others.
Without precise data according to ages at the department level, it is impossible at this stage to go further in the interpretation.