Covid-19: contagion, delta mutation… You have to worry about the CH.1.1 variant. Who is in the UK?

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A new variant of Covid-19 has been detected in the Kingdom. CH.1.1 has a mutation that already belonged to the Delta variant. This new strain raises fears of an increased risk of infection.

This has been a constant for a few weeks: the health authorities of the various European countries have increased their epidemiological surveillance, partly for fear of the emergence of a new variant of Covid-19. The outbreak of the epidemic that swept China in late 2022 raised fears of the emergence of a new strain of the virus. In Europe, UK health authorities have warned of a new variant of SARS-CoV-2: CH.1.1 (also called “Orthos”, an unofficial name). The midi dispatch looks back on the recent discovery of this new strain.

What do we know about this new subvariant?

This BA.2 sublineage, belonging to the Omicron variant family, was identified last November in south-west Leicestershire, UK. According to UK health officials, on December 25, CH.1.1. accounted for 16% of the Covid-19 contamination in the country. That number rose to 20% in January. in one epidemiological point published on January 11thThe UK Health Security Agency (UKHSA) claims that this strain could even “become dominant in the UK unless new new variants emerge”.

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For the time being, the World Health Organization (WHO) has not classified this variety as a “variant of interest”. “Currently, with hindsight, it appears to be lacking in pathogenicity,” co-comments Christine Rouzioux, a virologist and member of the National Academy of Medicine The midi dispatch. However, this variant has already been detected in France: gem the latest epidemiological update from Public Health Francepublished on January 11th, CH.1.1 currently represents 1.3% of the Covid-19 contaminations.

Do we need to worry about this?

This new strain is of great interest to researchers, and with good reason, although it belongs to the Omicron family, it carries a mutation that has already been observed in the particularly virulent Delta variant. This mutation (designated P681R) “brings about changes in the protein structure of the virus,” Christine Rouzioux continues. And could therefore allow the virus to attack cells more violently. However, this is not a first: “We have already observed this type of mutation in variants of the Omicron family, explains Christine Rouzioux. This is a point that surprises us and interests us. Of course, this variant requires monitoring.”

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What virologists are most interested in is above all the transmissibility of this new strain: “Immune escape is the only real criterion that can lead to an epidemiological recovery, one estimates The midi dispatch Virologist Bruno Lina. And the latest studies on the transmissibility of CH.1.1 show that it is significantly less contagious than the XBB.1.5 variant.”

Therefore, at first glance, the CH.1.1 variant does not appear to pose a risk of epidemiological recovery in Europe. Professor Bruno Lina also explains that in this context, an epidemiological recovery would only be considered if there was a drop in collective immunity. “This is a scenario that one can probably imagine for the coming semester,” emphasizes Professor Bruno Lina.

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