“Subvariant”. This new term was pronounced several times last week by public health authorities. Indeed, a “cousin” of the Omicron variant has appeared on the experts’ radar. This new mutation does not seem, for the moment, more dangerous.
Omicron BA.2 is a slightly different form of Omicron B.A1 (the one currently circulating the most). A few dozen cases have been detected in Canada and Quebec.
This sub-variant is described as “stealth” by many scientists, because mutations would give it the property of evading screening tests by a process called “failure to amplify the target of the gene S”.
In a PCR test, “small molecules stick to the genetic background of the virus and make it possible to amplify the signal, explains virologist Benoit Barbeau. A chain reaction allows only a small amount [de virus] can be detected. »
If these molecules no longer correspond to the genetic background of the virus, which has become too different, there is a greater chance of creating false negatives. This flaw has already been spotted by scientists who are working to recalibrate the screening process to include this BA.2 subvariant.
“We probably underestimate [le nombre d’Omicron BA.2 qui circule] because of that, ”confirms Benoit Barbeau. According to him, there is no reason to be alarmed by this phenomenon.
The acting national director of public health, Dr. Luc Boileau, did not seem unduly worried about the appearance of the sub-variant. “We do not believe that this will overturn the deconfinement plans. […] Probably it’s more contagious. The data so far does not show that it would be more dangerous in terms of the number of hospitalizations, or more lethal,” he said.
Omicron BA.2 has been detected in at least 54 countries.
The Omicron group
This is not the first time that a sub-variant has been detected. The “Delta plus” was briefly talked about last year, before disappearing in favor of more resistant strains.
What is called the Omicron variant would in fact itself be a sub-variant, according to Benoit Barbeau.
“There is a strong belief that there was a common ancestor that was created in early 2021, then evolved into different sub-variants, to appear in South Africa in November and December back home. »
This is how from a common ancestor would have been born at least three Omicron sub-variants: the B.A1, the B.A2 and the B.A3.
This “Omicron group” really stands apart from the other groups of variants, because it has a very large amount of unique mutations that distinguish it from the other forms that SARS-CoV-2 takes.
“There are as many variations between the sub-variants of the Omicron group as when we talk about the Alpha versus Delta variant,” observes Mr. Barbeau. It shows that there are more adaptations on the part of this virus than previously thought. »
This text is taken from our newsletter “Coronavirus mail” of February 1, 2022. To subscribe, click here.