Omicron wave: the epidemic peak is long overdue



While the peak of the epidemic wave linked to the Omicron variant was scheduled for mid-January, the number of contaminations in France continues to increase. On January 21, there were more than 350,000 daily positive cases on average over the past seven days. Hospitalizations also continue to grow, even if the number of intensive care admissions decreases: on average, 289 daily admissions, a decrease of 9% compared to the previous week.

→ ANALYSIS. Covid-19: “Test, trace, isolate”, a strategy undermined by Omicron

This contrasting situation can be better understood through regional developments. “We are surely going through epidemic peaks in several regions”explains Yannick Simonin, virologist and teacher-researcher at the University of Montpellier. “Omicron did not arrive everywhere in France at the same time, for example Île-de-France was affected much more quickly than the south of France. » Thus, in Seine-Saint-Denis, the number of contaminations fell by more than 20% in seven days, while in Pas-de-Calais they increased by 55% over the same period, reported the Covidtracker site.

The majority BA.2 subvariant in Denmark

Added to this is the detection of a sub-variant of Omicron, BA.2, which complicates the passage of the peak. A priori, BA.2 would be more contagious without being more virulent. But there are still many unknowns, such as the precise impact of this sub-variant on severe forms of Covid. Or the fact of knowing if one can be recontaminated by BA.2 after having been contaminated by Omicron. ” It is still too early to be able to draw conclusions on this sub-variant”, thus explains Philippe Amouyel, epidemiologist at the Lille University Hospital, who calls for caution. Corn ” for the moment, with the data we have, it does not fundamentally change the situation “, reassures Yannick Simonin.

In Europe, the United Kingdom and Denmark have higher BA.2 contamination rates than France. And if, across the Channel, contaminations by this sub-variant are still largely in the minority compared to Omicron, they have become the majority in Denmark. “ There is no great stress to havebecause, in the countries where it is more present, there have been no major repercussions “, confirms Yves Coppieters, epidemiologist and professor of public health at the Free University of Brussels.

Sequence to better track variants

For the specialist, it is more the delay of France on the sequencing of the genomes and therefore of the variants which poses a problem: “ Compared to the United Kingdom or Denmark, France maps much less the share of each variant in the total contamination. France carries out “Flash surveys” at regular intervals which provide a snapshot “at a given time” of the distribution of variants on the territory. “ It is true that at the start of the pandemic, France was one of the bad students for sequencing, relativizes Yannick Simonin. But today, we will not miss the arrival of a new variant or sub-variant. »

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