CORONAVIRUS – Faced with the rain of positive cases, the government is trying to continue monitoring the progress of the wave of Covid-19 linked to the Omicron variant while “making life easier for parents and teachers”.
Because for the moment, the figures for the coronavirus monitoring indicators are still on the rise and the peak is not yet there. Neither at the level of cases, nor at the level of hospitals, while the Omicron variant causes less serious forms, without this making it possible to ensure that the services will not be saturated. More details on this in this article.
To fully understand where France is facing the Covid-19, Then24 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 on Tuesday 11 January are those published the day before, Monday 10.
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
Monday January 10, the Directorate General of Health has identified 93,896 positive cases, a low figure which can be explained by the fact that we test a lot less on Sundays. Last week on the same day, 67,461 cases had been identified. If we look at the average evolution (over 7 days, the blue curve), we see that the fifth wave is still advancing at a spectacular pace (more than 269,000 on average, a record), swollen by contaminations linked to the Omicron variant.
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 first graph below shows the share of the Omicron variant and the Delta variant in positive cases. As can be seen, Omicron has imposed itself, but Delta has not completely disappeared and continues to lead to tens of thousands of cases every day.
The graphs below show the incidence, as well as other essential indicators to monitor the evolution of the epidemic. We see for example that new hospitalizations are climbing again at a significant rate, with the peak of the third wave almost passed. For the first time, the positivity rate is close to 20%.
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 are on the rise. But the most important thing is to understand how fast this evolution is or how much it decreases. For that, it is interesting to look at the evolution over a week, in percentage, of these figures:
The incidence rate continues to increase (purple bars are climbing), but less quickly than previously. Public holidays and important scouting can create some bias, which is why it is important to check that the trends continue over time. It is only once the purple bars are down that we will be able to say that the peak of this 5th (or 6th) wave has been reached. It is hoped for mid-January at the level of contaminations.
Regarding hospital indicators (which are estimated to have between 10 and 15 days lag on health indicators), intensive care occupancy rate neighbor the 75%. If this rate remains lower than the previous waves, it continues to climb and the number of occupied beds is increasing every day.
The Omicron variant changes the shape of the wave
As incidence and positivity explode, why are hospital indicators not in the bright red? Again, because the Omicron variant is a game-changer, as its severity is less. It is difficult to know to what extent this drop in virulence is linked to its mutations or to the fact that it infects vaccinated people, and therefore highly protected against serious forms.
Still, the stall between cases and hospitalizations or resuscitations is obvious. The graph below shows the evolution of the number of cases, hospitalizations and intensive care admissions in percentage compared to the highest reached during the second wave of Covid-19, in November 2020.
Before the arrival of this new variant, the highest number of cases had been reached in early November 2020, for the second wave. For hospital indicators, the peak took place in early April 2020, at the time of the first wave.
As we can see, the difference between the cases and the hospitalizations or entries in intensive care is obvious with Omicron. Before that, lighter divergences are visible between the waves. They are difficult to explain with certainty, but several tracks can be mentioned: the severity of the Alpha and Delta variants, the evolution of the vaccination campaign, etc.
The map and graph below shows Omicron’s dominance across the country. Even if some regions are more affected than others, the variant is gaining ground everywhere.
Map of the incidence rate by department
If we look at the evolution of the epidemic in a more local way, we see that the trend is still on the rise, and that the incidence is on the rise in almost all departments as can be seen on the map below which shows the evolution of the incidence rate over one week.
In France, all departments are above the 1000 incidence rate threshold. The 3,000 mark, if not 4,000, has even been reached in many departments.
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, the intensive care occupancy rate is now over 50% in all regions except Normandy. The tension is very clear in Paca and Corsica where there are more patients than normally available space. Patient transfers have already taken place.
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 it should already be remembered that an increase was foreseeable from the beginning of autumn with the dominance of the Delta variant, much more contagious. Since then, the Omicron variant has come to play the spoiler.
A controlled rise in the epidemic in the middle of winter, with limited measures (such as the health pass, wearing a mask, ventilating enclosed places, etc.) was 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, 78% of the population is doubly 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 the infection decreases over time, especially six months after vaccination, and even more with the Omicron variant. 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 fulgurance of the Omicron variant makes this third dose even more essential, around 42% of the population have already received it.
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 unvaccinated), we can see that the vaccine is very effective.
The proof with the graphics below. We also see that the booster further increases the effectiveness of the vaccine.
See also on Then24: how to properly use a self-test?