Science

“Good against antibodies”: BA.2.75.2, a new sub-variant that worries scientists

As health authorities announce an eighth wave of the Covid-19 epidemic in the coming weeks, research teams have identified a new sub-variant of Omicron that appears to be more resistant to vaccine-induced immunity.

Since its introduction, the strain Omicron (B.1.1.529) has given rise to several sub-variants of the same name, including BA.1, BA.2 or even BA.1.1 and BA.4.6. Today it is the BA.5 footprint, accounting for 83% of pollution worldwide and 95% in France. The new one was identified as BA.2.75.2. According to several virologists, this could be “the next option.”

What do we know about this sub-option of BA.2.75.2?

It was first identified in July in India, where it currently dominates and is gaining momentum in Japan and Singapore. It is currently present in fifteen countries including Chile, England, USA, Spain and Germany. For now, this new sub-variant of Omicron will only represent 0.5% of the coronaviruses sequenced worldwide in the past three months. “It is not trivial to see that although it is dominant in certain regions of India, it has already appeared in other parts of the world,” notes Kristin Ruziu, Emeritus Professor of Virology at the Necker Faculty of Medicine and a member of the Academy, in L’Express. medicine.

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“In France, detection of BA.2.75 remains low, at a maximum of 0.3%,” the French Health Service points out in its latest risk analysis of new variants on 7 September. “Only 22 sequences of the BA.2.75 subline were found in metropolitan France,” the document states. But this does not mean that it does not require enhanced control. Other sub-variants of Omicron, initially a minority, later took over the infestation. “The evolution of the detection of BA.2.75 throughout the territory and at the regional level is under close observation,” France’s public health further highlights.

Some questions regarding its characteristics, in particular transmission and pollution, still remain unanswered. “We are still missing a retrospective,” explains Christine Ruziou, who also welcomes the international surveillance organized around Covid-19 mutations. However, Indian scientists report that there is currently no significant increase in direct hospital admissions to regions where it circulates.”

Why is Omicron still dominating?

Omicron is the thirteenth Sars-CoV-2 variant since the discovery of the first strain in early 2020. This Greek alphabet designation was required by the World Health Organization (WHO) to qualify and classify most variants. virus. But since its introduction last November, it seems like Omicron has pretty much dominated. “The big Omicron family doesn’t seem to have finished talking about it yet,” said Antoine Flahaud, an epidemiologist, director of the Institute for Global Health and professor at the Faculty of Medicine in Geneva. “BA.1 entered in December 2021 causing a very significant wave of pollution peaking at the end of January 2022 in France, followed by BA.2 in April and BA.5 in July. the BA.5 variant from Omicron is currently returning to provoke a new autumn wave in Western Europe,” the epidemiologist clarifies. Several other Omicron sub-variants are of concern to the scientific community, including BA.4.6.

“The intense epidemic activity since Omicron became the dominant variant on the entire planet is due to the very high concomitant transmissibility of its ability to evade the immune response,” notes Antoine Flao. These two determinants seem to explain dominance without separating Omicron from his subordinates. options around the world within ten months.” This does not mean that Sars-Cov-2 stops mutating, but it does mutate differently. “Based on what is being discovered right now, it looks like the future SARS-CoV-2 will originate from Omicron,” David Robertson, a virologist at the University of Glasgow, told The New York Times.

Could this undermine our vaccine immunity?

According to the first two studies, not yet peer-reviewed, one being a Swedish-British study and the other a Peking University study, the ability of sub-variant BA.2.75.2 to neutralize antibodies is very strong, especially when compared to vaccines already on the market. . In other words, it can easily suppress our immune responses. “We have never seen a virus so resistant to neutralizing antibodies and monoclonal antibodies that were effective before, including against AD 5,” says virologist Cristin Ruziou. And for good reason: it has about nine additional mutations in the Spike protein, the entry point, also called the key, that allows the virus to enter our cells. This characteristic can make it more contagious.

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In fact, it may reduce the effectiveness of new vaccine formulations. But according to Public Health France, “The Omicron BA.2.75 subline is under special surveillance by the international community based on its mutation profile and no epidemiological or clinical alarms have been associated at this stage.” Although it is not excluded that this happens. “The real problem is that immunity is weak or not even protective against this variant. It has a real ability to elude the immune system,” concludes Christine Ruziou.

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