Covid-19: contagion, Delta mutation… should we be worried 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 a risk of contagiousness of increased dangerousness.

This has been a constant for several weeks: the health authorities of the various European countries have increased their epidemiological surveillance, fearing among other things the appearance of a new variant of Covid-19. The epidemic outbreak that hit China at the end of 2022 raised fears of the emergence of a new strain of the virus. In Europe, British health authorities have alerted to the presence of a new variant of SARS-CoV-2: CH.1.1 (also called “Orthos”, a name that is not official). The Midi Dispatch looks back on the recent discovery of this new strain.

What do we know about this new sub-variant?

This BA.2 sublineage, which belongs to the Omicron variant family, was identified last November in south-west Leicestershire in the UK. According to British health authorities, on December 25, CH.1.1. accounted for 16% of Covid-19 contaminations in the country. This figure rose to 20% in January. In an epidemiological point published on January 11, the “UK Health Security Agency” (UKHSA) thus affirms that this strain could even become “dominant in the United Kingdom, unless new new variants appear.”

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For the time being, the World Health Organization (WHO) has not categorized this strain as a “variant of interest”. “There is currently an obvious lack of hindsight to know its level of pathogenicity”, comments Christine Rouzioux, virologist and member of the National Academy of Medicine, with The Midi Dispatch. However, this variant has already been detected in France: according to the latest epidemiological update from Public Health France, shared on January 11, CH.1.1 currently represents 1.3% of Covid-19 contaminations.

Should we be worried about it?

This new strain is of great interest to researchers and for good reason, although it is part of the Omicron family, it has a mutation that has already been observed in the particularly virulent Delta variant. This mutation (called “P681R”) “brings modifications to the protein structure of the virus”, continues Christine Rouzioux. 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 on variants belonging to the Omicron family, explains Christine Rouzioux. This is a point which surprises us and which interests us. This variant obviously requires supervision”.

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What interests virologists the most is above all the transmissibility of this new strain: “Immune escape is the only real criterion that can lead to an epidemiological recovery, estimates with The Midi Dispatch virologist Bruno Lina. And the latest studies looking at the transmissibility of CH.1.1 show that it is significantly less contagious than the XBB.1.5 variant.”

At first glance, the CH.1.1 variant does not therefore seem to represent a risk of epidemiological recovery in Europe. Professor Bruno Lina also explains that in this context, epidemiological recovery would only be considered in the event of a decline in collective immunity. “It’s a scenario that can probably be envisaged by the coming semester”, punctuates Professor Bruno Lina.

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