Are we heading towards a real recovery of the Covid-19 epidemic in France or are we witnessing a simple rising plateau? The Minister of Health, Olivier Véran, reported this Friday March 11 of a “rebound” of the epidemic. “Given the latest figures from yesterday, it’s a 20% increase,” he said. The number of new positive cases stood at 74,818 on Thursday, according to Public Health France, against 60,225 a week ago.
At a time when the incidence rate is rising again in France in certain departments, and when most of the health protection measures will be lifted from Monday, such as the end of the vaccination pass and the mask indoors – except in the public transport, the Institut Pasteur details several scenarios for the coming weeks in its new models unveiled Thursday.
With the end of the health restriction measures, the Institut Pasteur anticipates that the French will increase their contacts and thus promote the circulation of the virus. “The relaxation of control measures on March 14 is expected to further push transmission rates up,” the document reads. However, there is encouraging news: whatever the magnitude of the future release, the researchers envisage a peak in contaminations much lower than that observed at the beginning of this year.
“Across all scenarios explored, the peak in cases remains well below the January peak,” the report read. In January, during the peak of contamination, more than 300,000 cases were detected daily. This peak “could exceed 100,000 daily cases in March in scenarios where transmission rates increase very significantly following the relaxation of control measures”, write the modellers. They explored scenarios where, starting March 14, transmission rates are 50%, 70%, 100% or 130% higher than January-February levels.
In the event that transmission rates become 130% higher than those of January-February, the worst case scenario (in purple), France could then record more than 150,000 cases per day. The Pasteur Institute also presented a scenario in which “the French could anticipate the relaxation of measures, with an increase in contacts occurring before March 14”. But, in this case, the difference would not be significant.
“Too optimistic” projections?
If there was a sixth wave, the new epidemic peak should in any case occur quickly, shortly before the beginning of April, and this before the curves drop again, according to the Institut Pasteur, which does not project beyond April 1st.
The French foundation points out the limits of its models linked in particular to the Omicron variant, hegemonic, and more particularly the BA.2 sub-lineage, more transmissible than BA.1, and which already represents 52% of the contaminations detected in France. “We hypothesize that people infected with an Omicron virus are immune to Omicron reinfections for the duration of the simulations (until April 1, 2022),” she explains. “Furthermore, we do not model the gradual decline of immunity, which could make our projections too optimistic. We also do not model the impact of climate. In order to make longer-term projections, it will be important to take into account the decline in immunity and the effect of climate on epidemic dynamics”, warn the researchers.
The Institut Pasteur also warns that “the spread of the SARS-CoV-2 virus is difficult to anticipate and that the dynamics of the epidemic can change quickly”. Despite everything, “in the short term, there is no reason to have major concerns,” Mircea Sofonea, epidemiologist and lecturer at the University of Montpellier, told L’Express on Wednesday. “Even if there is a rebound, it should remain limited in magnitude.”