Is it too early to take off your mask? Monday March 14, most of the anti-Covid restrictions are lifted. But for several days now, certain epidemic indicators have no longer dropped, or even increased, engaging the executive in a balancing act. “The end of obligation does not mean the end of vigilance”said Olivier Véran, traveling to Sables-d’Olonne (Vendée). “I invite French women and men to wear the mask in all circumstances which may expose them or those around them to the risk of contamination”said the Minister of Health.
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Simple plateau, slight rebound, or the beginnings of a new wave? Too early to say. But PTo understand this epidemic quivering, franceinfo takes stock, with supporting graphics.
Contaminations and hospitalizations up slightly
The point on the main indicators, first. The number of new cases of Covid-19 had reached a record at the end of January, with more than 366,000 contaminations per day on average. This figure then experienced a continuous decline, until the beginning of March, when it failed to drop below the 50,000 on a rolling average. For ten days now, we have even seen an increase in new cases: there were 65,000 per day on March 13.
As for new hospitalizations, the indicators have stopped decreasing. After peaking at more than 2,900 hospital admissions in early February, this figure fell to an average of 950 in early March, but a plateau has been observed for more than a week. Even a slight increase: on average on March 13, there were 973 new hospitalizations per day.
These are the only indicators whose evolution is, for the moment, in the red. As shown by our dashboard, which tracks all the figures for the Covid-19 epidemic, intensive care admissions and deaths continue to decline after the peak in early February. And it is precisely the evolution of serious forms that will be scrutinized in the coming weeks.
The more contagious sub-variant BA.2 is predominant
How can this epidemic quivering be explained? Member of the Scientific Council, Arnaud Fontanet, director of the epidemiology of emerging diseases unit at the Institut Pasteur in Paris, offers a first explanation: “a sub-variant of Omicron, BA.2, which is more contagious than its predecessor”he explained on France Inter, Monday. “The Omicron BA.2 variant is 30% more transmissible” than the Omicron BA.1 variant, also explained Yazdan Yazdanpanah, head of the infectious diseases department at Bichat hospital in Paris and member of the Scientific Council.
In fact, while the Omicron BA.1 sub-variant had been in the majority since the end of December, its cousin, the BA.2, is gradually replacing it. It was already in the majority in India or Denmark, from the end of January. According to provisional data from the Flash surveys of Public Health France, it represented 52% of contaminations the week of February 28.
A resumption of contamination over the back-to-school period
Another explanation put forward by the same specialists: the end of the holidays. “The regions where the incidence has started to rise again are those which returned from vacation on February 21”, detailed Arnaud Fontanet on France Inter. Zone B, including in particular Hauts-de-France, Grand Est, Paca or Brittany, has actually experienced an increase in incidence since that date. Similarly, in the regions of zone C (Ile-de-France and Occitanie), there is an increase in contamination from March 7, the date of the end of the school holidays.
Reassuring but incomplete projections
“This rebound is not a wave”, however assured the Minister of Health, Olivier Véran. Based, no doubt, on the projections made by the Institut Pasteur published on March 10. Their authors believe that “in all scenarios explored, the peak of cases [en mars] remains well below the January peak.” Other specialists also want to be reassuring. “There is an immunity that has set in”relativizes Yazdan Yazdanpanahbecause there is “more than 80% of people vaccinated, 50% who had a booster dose, and a significant part, estimated at 40%, of the population already affected by the infection”.
In addition, the fourth dose of vaccine, which is now open to those over 80 whose third dose dates back more than six months, “is important” for “durability of immunity”, insists the infectiologist.
That being said, many unknowns remain. The Institut Pasteur study did not include “the progressive decline of immunity, which could make” projections “too optimistic”, specify its authors in the preamble. Likewise, “climate impact” was not taken into account in these models, while major epidemic waves affected France in the spring of 2020 and 2021.