Omicron BA.2 now exceeds 50% of contamination in France. It appears to be somewhat more contagious than Omicron BA.1, the currently dominant strain.
During the winter of 2021/2022, the Omicron variant of covid very quickly began to circulate around the world. Finally, it replaced the Delta variant at the beginning of 2022, in front of a 99% majority in France. The reason: increased transmissibility. We now know that Omicron is indeed much more contagious than the previous variants, while causing less severe forms of Covid-19 disease. However, Omicron represented a problematic public health issue: the more people are infected, the greater the risk of serious cases in the population and therefore of hospital stress.
There are several sub-lineages of the Omicron variant, that is to say cousin variants, which genetically resemble it except for a few mutations. One of them was already particularly watched: Omicron BA.2, whose first data seemed to show small significant differences with its big brother, although it was not particularly worrying in itself.
In a flash survey by Public Health France, broadcast on March 11, 2022, we now learn that Omicron BA.2 is on the way to becoming the majority.
Omicron BA.2 accounts for 52% of contamination
We can read in the Public Health France report that Omicron BA.2 was up 48% two weeks ago, and that, in the week of March 7 to 11, 2022, it represented 52% of contaminations. Still at the beginning of January 2022, this strain did not however exceed 10% of contaminations.
Having now crossed the 50% stage, Omicron BA.2 has not yet replaced its “big brother” Omicron, but this marked increase suggests that it could in turn become the dominant variant in a few weeks. How to explain this acceleration?
The data on Omicron BA.2 remains “preliminary” in the scientific sense at this time. However, these data seem to indicate that it has an increased contagiousness. This is what the Danish researchers have put forward, concluding, in a pre-publication study, that Omicron BA.2 “ is inherently much more transmissible than BA.1 “. They also write that it also has immuno-evasive properties, that is to say that it more easily escapes the immunity already conferred against covid.
Same observation in a study in England: “ BA.2 has demonstrated an increased rate of increase over BA.1 in all regions of England “, notes a report from the British Ministry of Health. However, this English report, like research in Denmark, does not highlight an increased risk of serious forms: “ The preliminary analysis finds no evidence of a greater risk of hospitalization following infection with BA.2 compared to BA.1. »
Clearly, it would seem that BA.2 is distinguished by a greater ability to infect hosts, without however causing more serious forms. This would explain this gradual replacement of the first strain of Omicron by this second strain. Potentially, this could also be seen as an explanation for what appears to be an epidemic rebound since early March 2022.