Omicron BA.2.75 is alarming! Experts point 3 key reasons why tracking new COVID variant is essential

With detection of a new sub-variant of Omicron - BA.2.75 in several states, experts have pointed out that its emergence is ‘alarming’ as ‘because it may imply a trend to come.’ However, it is still too early to predict whether it will tend to become a dominant strain. So far 10 states have reported BA.2.75 variants including Delhi and Maharashtra, which saw massive surge in infections during previous waves. Indian Health Ministry is yet to officially confirm the detection of the sub-variant in the country.

So far 85 sequences of the sub variant from eight countries (including India) have been reported. And speaking regarding the same, Dr. Shay Fleishon of the Central Virology Laboratory at Sheba Medical Center in Tel Hashomer said, it is "too soon to tell" whether BA.2.75 will be the next dominant variant, he noted that the sub-variant may be "alarming because it may imply a trend to come".

Admiting with him, Thomas Peacock, a scientist at Imperial College London, also said sub-variant is worth "keeping a close eye" on

Why the emergence of the new variant can be alarming?

Explaing the logic behind it, Fleishon explained in the recent past there has been a trend of second generation variants based on Omicron sub-lineages, namely BA.1, BA.2, BA.3, BA.4, and BA.5. This was based on Omicron lineages with mutations in the S1 section of the spike protein and specifically in the part of the spike protein which the virus uses to connect to and gain entry into cells.

And to note, how the new variant differs, he said, till now, the rise seen in these sub-variants has been "at a level not seen in second-generation variants from other variants of concerns".

Also these second-generation variants have only been found in a few cases within one region. This is the first time a second-generation variant from Omicron has spread to multiple regions. "The fact that such a divergent 2nd gen variant can succeed inter-host is alarming. It means that if BA.2.75 will not succeed, and even if it will, other 2nd gen might grow better over time," Fleishon said.

Meanwhile, Bloom Lab at the Fred Hutch research institute in the US, that flagged the new variant, pointed to two mutations as key: G446S and R493Q.

"G446S is at one of most potent sites of escape from antibodies elicited by current vaccines that still neutralises BA.2. So for immunity from vaccines or early infections, adding G446S to BA.2 will decrease neutralisation," the lab said.

"However, G446S will have less effect on antibodies of people with prior BA.1 breakthrough infection. Therefore, BA.2.75's antigenic advantage relative to BA.2 will be most pronounced in people who have not had BA.1 exposure," it said.

This means that "BA.2.75 will have antibody escape that is similar to that for BA.4/5 with respect to the current vaccine".

The R493Q mutation, on the other hand, seems to increase the virus's ability to attach to ACE2 -- the protein which the Covid virus uses to enter cells.