The figures for the Covid-19 epidemic are often very interesting to analyze, and this is particularly the case of those posted online this Friday by the Ministry of Health. For the past month, the Directorate of Research, Studies, Evaluation and Statistics (DREES) has published weekly the numbers of positive cases, hospitalizations, and critical care admissions according to vaccination status. Now, they are also available by age group. This avoids the bias of having only all ages combined in the same statistics, given that the vaccines are not as effective according to the profiles or the date of the injection (protection decreases with time and the older were vaccinated as a priority).
The Drees has distinguished five age groups: those under 20, 20-39, 40-59, 60-79, and 80 and over.
What should we take away from it?
To summarize, regardless of the category, there have been throughout the last few weeks, for an equal population, many more positive cases, hospitalizations and critical admissions in unvaccinated people than in vaccinated people.
Beware of interpretations
For example, on August 22, among those aged 80 and over, there were eight times as many daily hospital admissions each day of patients diagnosed with Covid-19 in a group of 10 million unvaccinated people, than in a group of 10 million fully immunized people.
Namely, respectively, 744 and 94 daily hospitalizations.
In the 60-79 age group, the multiplying factor is 22 (677 hospitalizations for 10 million unvaccinated, 31 for 10 million vaccinated).
Among 20-39 year olds, it is 29 (166 and 6 respectively).
Note that we only take into account patients who test positive and not all those with suspicion of Covid-19, but the reports are similar.
And among those under 20, the numbers are too low to be able to have reliable data.
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The evolution in curves shows that over the course of this fourth wave and until August 22, there were always - with an identical population - more unvaccinated patients than vaccinated patients who were admitted to hospital.
This is true for all regions and we find similar results for positive cases and critical care admissions.
That is to say that in each age group, always with an equal population, each time there are more patients who test positive and patients in a very severe condition among the unvaccinated than among the vaccinated.
Read also Covid-19: these pro-vaccination arguments from the government to be handled with caution
These data are invaluable and they confirm that vaccines are protective, but be careful not to misinterpret them. To take our first example, the fact that there are 8 times more hospitalizations of unvaccinated than of vaccinated in people aged at least 80 years does not mean that a vaccinated has - precisely - 8 times less. risk of being hospitalized. The data from the DREES are simple "descriptive statistics" at time T, as indicated by the Ministry of Health. This factor 8 (or any other) is "a true value at the scale of a population, (...) but it should not be transformed into an individual probability", recently told us a researcher who insisted on remaining anonymous.
