SCIENCE – The countdown is on. Christmas is two weeks away and the epidemic situation linked to Covid-19 is not improving. If all the indicators are increasing (from the incidence rate to hospitalizations, including the number of intensive care units which are on the rise), the situation is not yet critical in hospitals.
To prevent it from becoming so, the government is trying to strengthen its vaccine shield. Since Tuesday, December 7, French people over 65 can get a booster dose of vaccine without an appointment. From December 15, vaccination will also be open to 5-11 year olds “at risk” of developing serious forms of the virus (obesity, diabetes, recent cancer, etc.).
To fully understand where France is facing the Covid-19, The HuffPost invites you to look at the latest figures, but especially their evolution in maps and curves. An important point to keep in mind before reading further: the data is always published in the evening. Thus, the figures up to date this Thursday, December 9 are those published the day before, Wednesday 8.
You should also know that these are not the figures for the day, but those on D-1 for the number of hospitalizations and the number of new confirmed cases. For the incidence and the positivity rate, the screening figures on D-3 (on the date of the test) are used.
National Covid-19 curves
Wednesday, December 8, the Directorate General of Health identified 61,340 cases. If we look at the average evolution (over 7 days), we see that the fifth wave is close to 50,000 new cases per day. A level in the third wave of this summer. You have to go back to November 2020 to find such figures. A clear and strong increase visible on the curve below:
The figures on D-1 are practical for following the evolution of the epidemic as closely as possible, but are likely to vary from one week to another depending on the speed of the results. To be sure of the trends, it is best to look at the data published by Public Health France, which shows the number of cases on the date of screening, with a delay of three days.
The graphs below show this indicator, as well as other essentials to follow the evolution of the epidemic. We see that while hospitalizations are increasing, they are progressing less quickly than cases, especially thanks to vaccination.
Meaning of the different indicators
- Incidence rate: this is the number of cases detected per 100,000 inhabitants. It is very useful, because it gives an inventory of the epidemic in near real time (a few days delay for the appearance of symptoms, or even before their appearance for contact cases). But it is dependent on the screening skills.
- Positivity rate: it is the number of positive tests compared to the total tests carried out. It makes it possible to “control” the incidence rate. If there are many cases in a territory (incidence rate), but this is only due to highly developed screening, the positivity rate will be low. Conversely, if it increases, it means that a greater proportion of people tested are positive, but above all that the infected people who are not tested, who fall through the cracks, are potentially more numerous.
- Resuscitation bed occupancy rate by Covid-19 patients: It is a figure scrutinized, because it allows to know if the hospitals are able to manage the influx of patients. It is very useful because there is little risk of bias: it does not depend on screening and bed occupations are well reported to the authorities. Its disadvantage: there is a significant delay between contamination and going to intensive care, of about two to three weeks.
- Intensive care admissions and new hospitalizations: smoothed average over 7 days of people entering the hospital
- Death in hospital: Like resuscitations, it is a fairly reliable indicator, but with a significant delay.
- R effective: this indicator represents the real “virus reproduction rate”, ie the number of people infected by a contagious case. It is calculated by epidemiologists and also has a significant delay.
As we can see, all indicators have been on the rise for several days. But the most important thing is to understand how fast this development is. For that, it is interesting to look at the evolution over a week, in percentage, of these figures:
The incidence rate is still on the rise, but growth has been weakening for several days.
As for hospital indicators, the intensive care occupancy rate is even lower than during big waves (48%), but the number of occupied beds is increasing every day. The same goes for hospitalizations.
Map of the incidence rate by department
If we look at the evolution of the epidemic in a more local way, we can clearly see that the trend is on the rise in an overwhelming majority of metropolitan departments, but with marked differences between the territories., as can be seen on the map below, which shows the evolution of the incidence rate over one week.
In France, all departments have exceeded the 100 incidence rate threshold. And the figure of 500 has now been reached in around twenty territories.
The graph below allows you to analyze the situation in your department in more detail.
The intensive care occupancy rate map
As for hospital indicators, no region is currently in tension because of the Covid-19. The intensive care occupancy rate is now over 50%, except in Brittany, Normandy, Île-de-France, Hauts-de-France, New Aquitaine and Occitanie.
A very effective vaccination, but which slips
How to explain this fifth wave? Difficult to say as the coronavirus succeeds in thwarting our forecasts, but we must already remember that an increase was foreseeable, especially with the dominance of the Delta variant, which is much more contagious.
A controlled increase in the epidemic in the middle of winter, with limited measures (such as the health pass, wearing a mask, ventilating enclosed places, etc.), is only possible thanks to vaccination. If the vaccine does not protect 100%, it reduces the risk of infection and drastically lowers the risk of developing a severe form of Covid-19.
Today, more than 76% of the population is vaccinated, as can be seen in the graphic below, with disparities between age groups.
But we now know that the effectiveness of the vaccine against infection declines over time, especially six months after vaccination. Protection against severe forms of Covid-19 remains high, but still seems to be decreasing, especially in the elderly.
This is why many countries including France have launched a recall campaign. In its forecasts for the end of November, the Institut Pasteur estimates that a booster dose, by further reducing the risk of hospitalization of those most at risk and by reducing the risk of being infected, can lower the peak of hospitalizations in theory. Thus, a booster for those over 65 reduces the height of the peak by 20%, while a booster for all adults causes it to drop by 44%.
The following graph gives a better idea of the progress of the booster injections:
Vaccines still effective in the face of Covid-19
The effectiveness of the vaccines and the third dose is easily seen if we analyze the number of vaccinated or unvaccinated positive people, hospitalized or in intensive care.
However, we must be careful: more than 91% of adults are vaccinated. So it makes sense that there are a lot of people vaccinated in hospitals. But if we compare with equal numbers (how many hospitalized for a million vaccinated, versus how many hospitalized for a million non-vaccinated), we can see that the vaccine is very effective.
The proof with the graphics below. We also see that the booster increases the effectiveness of the vaccine even more.
See also on The HuffPost: how to control an epidemic, instructions for use