Unheard of since the start of the Covid-19 crisis.
More than 500,000 tests, precisely 502,528, were carried out last Friday in France.
This number, published Monday evening by Public Health France (there is always a three-day period for the information to be collected and consolidated), is twice that of the previous Friday.
And over the week of December 12 to 18, nearly 300,000 tests were performed daily on average, up 65% in ten days.
These tests can be PCR or antigenic, all being recorded in the same Si-Dep file since the beginning of December.
The latter are not announced day after day for the moment and the Directorate of Research, Studies, Evaluation and Statistics (DREES) simply reveals every Thursday information relating to the previous week.
Thus, from December 7 to 13, 1,384,057 test results were validated, including 265,929 antigens, or 19%.
This proportion, which has been growing continuously since the arrival on the market of antigenic tests in early November, could increase further.
How can we explain this sudden and strong acceleration of screening?
Several reasons are advanced, even if it is difficult to measure the precise impacts.
On the one hand, there has been a slight but continuous increase in the number of new daily cases for the past fortnight.
With the end of confinement on December 15, there are more contact cases that have passed a test (+ 13% from December 7 to 13 compared to the previous week, indicates Public Health France).
Get tested before the holidays
In addition, some people get tested when the holidays approach, whether it is to be able to fly to certain destinations or before going to find their family.
“Once they get tested and find they are negative, they self-contain for eight or ten days and they know they will be able to spend the holidays safe with their grandparents,” for example, ”indicates the president of the National Union of Biologists, François Blanchecotte.
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As the Scientific Council also recommends, for those who wish, to be tested one, two or three days before Christmas Eve, the number of tests could increase further this week.
These are not a priori antigenic, reserved primarily for symptomatic cases and contact cases.
Less sensitive, they do not always detect people with a low viral load.
“Yesterday [Monday], we were full of luck, to the maximum of our possibilities with 4,571 PCR tests in my laboratories”, testifies besides François Blanchecotte.
Massive screenings
"These people who are tested because they take the plane or plan to go to see their families are supposed to isolate themselves and not go out if they are positive, but they will not necessarily do it", thunders epidemiologist Catherine Hill, which has been arguing for several weeks for more extensive care of infected people.
The scientist also calls for organizing a massive screening of the population and testing a representative sample of inhabitants, as is already done in England.
There are indeed mass screenings organized in France at the moment, but only on a local scale or during targeted operations (for example in nursing homes).
This is the case, for example, in the Auvergne Rhône-Alpes region, where the number of tests has also increased significantly.
Between December 8 and 18, the number of daily tests (on average over the past week) more than doubled in fourteen departments.
If we do not have the daily details according to age, Public Health France noted in its last weekly epidemiological update that the screening rate had increased in week 50 (from December 7 to 13) in all categories, except among the 75-year-olds. and more.
Impact on the increase in new cases
As for the delays in obtaining the results, the situation has clearly improved.
There is hardly any need to wait three, four or even more days like last September.
From December 7 to 13, the verdict falls the same day or the day after the sampling for 95.9% of the PCR and antigen tests, indicates the Drees.
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This very strong increase in the number of tests also certainly impacts the much more moderate increase in the number of new cases per day.
To what extent?
Unable to answer at the moment.
During a remote press briefing last Friday, Public Health stressed that the proportion of symptomatic among those tested was stable in week 50 compared to that before.
We should know more in his next epidemiological update, scheduled for next Thursday.