On Tuesday, 18,000 cases of Covid-19 in 24 hours were announced, unheard of since May 19.
But can we really say that 96% of them were unvaccinated, as Jean Castex did this Wednesday at midday on TF1?
The Prime Minister, guest of the 13 Hours newspaper, citing this figure, wanted to encourage vaccination to face the "fourth wave" emerging in France.
This figure, however, has something to challenge.
Indeed, to our knowledge, the SI-DEP (positive cases) and VAC-SI (vaccination) databases do not yet provide such "cross-referenced" information on a daily basis.
A hazardous extrapolation
Matignon confirms to the Parisian that Jean Castex has taken over the results of a study by the Directorate of Research, Studies, Evaluation and Statistics (Drees), published Thursday, July 15.
This, carried out on all the positive cases identified from June 28 to July 4, had established that 96% of those among them who were symptomatic were not fully vaccinated.
In detail, 9% had received their first dose for more than 14 days or their second dose for less than 7 days, 4% had recently received their first injection, and 83% had received no vaccine dose.
Read alsoCovid-19 and Delta variant: what the first study says on the vaccination status of positive people in France
Jean Castex therefore made a somewhat hazardous extrapolation.
First of all, this 96% relates to a period dating from three weeks ago, when vaccination was less advanced and the Delta variant was less present.
Then, it only relates to symptomatic cases, and not to all positive cases (this rate then drops to 94%, according to Drees).
Finally, a portion of those 96% were indeed vaccinated, but with a single dose or a second dose less than seven days ago at that time.
Be careful not to misinterpret this indicator
It is not possible to say precisely what is the share of unvaccinated among the 18,000 positive cases identified in 24 hours between Monday and Tuesday.
But it should also be remembered that this kind of statistics, likely to strike the spirits, should be interpreted with caution.
The more the vaccination coverage increases, the more the proportion of vaccinated among the positive cases will be important, as our infographic shows and as we explained it at the end of June.
Taking the reasoning to the limit, if 100% of a population were vaccinated, 100% of positive cases (but also hospitalizations and deaths) would be vaccinated.
This is because vaccines are very effective, especially against severe forms of the disease, but not 100%.
