Omicron: BA.1, BA.2, BA.4, BA.5… what do we know about these new variants in circulation?

Public Health France conducted an analysis of the risk of new variants of SARS-CoV-2, the virus responsible for Covid. According to recent flash surveys in France, the Omicron BA.2 variant predominates in the region. Point location.

BA.1, BA.2, BA.3… The Omicron variant of Covid-19 continues to generate important sublineages. According to experts, this kind of coercion is an expected process.

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In the world today, Omicron is dominant in detecting new contaminations with 97.9% of the sequences in the global GISAID database. Its “almost exclusive” dominance is explained by its main feature: “a transfer advantage over previously circulating variants,” details Public Health France in its analysis. Immune escape also plays a role in competitiveness against other variants.

Clearly, the protection afforded by vaccines with Omicron declines more rapidly over time. Only severe forms of the disease appear to be relatively limited in the long term. This new variant after Delta would be less “immunogenic” than its predecessors, with a higher rate of re-infection.

5 Omicron sublines

The Omicron variant has five different subs now available in several countries. With “Omicron’s circulating density around the world”, this “genetic diversity” became an “anticipated phenomenon” for scientists.

In the BA.2 variant, a new mutation of Omicron, experts are calling for “different features.” Thus, the transmittance is higher and the generation interval, i.e. the delay between the two states, is shorter. BA.2, which is currently the majority in France, does not cause more serious forms of Covid-19 than the BA.1 type.

BA.4, BA.5: common features?

With regard to the detection of the BA.4 and BA.5 sublineages in early April, these new variants are being watched closely by scientists due to various mutations in the virus’s Spike molecule (F486V and R493Q). On the other hand, there is no reason to worry at the moment. In South Africa, these two subclades did not generate any new worrying traits.

Additionally, Public Health France conjures up the arrival of recombinants between BA.1 and BA.2, but don’t worry there too, “the probability of a recombinant BA.1/BA.2 having different properties is slim.” However, these new findings suggest that the “genomic surveillance” currently implemented is of “quality”.

Omicron and Delta’s XD recombinant under surveillance

But the good news is that three variants of “Alpha, Beta, and Gamma” are now classified as “non-circulating” on Earth, which has been designated “alarming”. So, in the last period from March 20 to April 19, their perception has drastically decreased. “These few detections could also be assignment errors in low-quality sequences,” he even details the public agency.

On the other hand, few strains have been or have been the subject of careful monitoring by scientists. This is the case of the XD recombinant of SARS-CoV-2. The latter combines Omicron and Delta. “Reinforced” oversight in France. According to the latest data, this new variant can reproduce more easily in the lungs of its host. On the other hand, it would not be more contagious than previous strains.

Other recombinants between Delta and Omicron have been identified: XF in the UK and XS in the United States. However, because their circulation was “very low in Europe”, Public Health France did not find it useful to include them in the classification.