New COVID subvariant BA.2.75 detected in India: Why we need to worry

The Omicron sub-lineage is believed to have certain mutations that let it dodge antibodies, giving it the ability to infect people who have had COVID before, as well as those who are vaccinated

New COVID subvariant BA.2.75 detected in India: Why we need to worry

India has recorded at least 46 cases of BA.2.75, as per the open-source database Global Initiative on Sharing All Influenza Data. AFP

India is currently witnessing a surge in COVID-19 infections — the nation added another 16,103 fresh cases on Sunday. With this, the active case tally now stands at 1,11,711, comprising 0.26 per cent of the total infections.

Medical experts believe the prevalence of three new and highly transmissible “offspring” of Omicron’s BA.2 subvariant — BA.2.74, BA.2.75 and BA.2.76 — is behind the current increase in COVID cases. They have flagged the BA.2.75 subvariant for special attention, due to certain mutations that let it dodge antibodies and attach itself better to human cells. This means that it has an increased ability to infect people who have been infected before, as well as those who are vaccinated.

Thomas Peacock, a scientist at Imperial College London, in a Twitter thread said that the variant is worth “keeping a close eye” on.

We take a closer look at the subvariant — its presence across India and the world and why it could be a danger in India’s fight against coronavirus.

BA.2.75 in India

As of date, India has recorded at least 46 cases of BA.2.75, as per the open-source database Global Initiative on Sharing All Influenza Data.

However, there’s no official word on the variant from either the Indian government or the SARS-CoV-2 Genomics Consortium (INSACOG), the genomic surveillance agency functioning under the health ministry.

This subvariant was identified and named by the international community based on investigations into BA.2 by scientists from Maharashtra, Karnataka and Jammu and Kashmir. An INSACOG scientist told Times of India, “We looked into how BA.2, which mainly triggered the third wave in January, was still causing breakthroughs and reinfections in June. That led to the finding of BA.2.75, which has more than 80 mutations, while BA.2 has about 60. Now, when we re-run old BA.2 samples for these newly identified mutations, we are finding BA.2.74, BA.75 and BA.2.76.”

Other than BA.2.75, India has also detected some 298 cases of BA.2.76 in India, followed by 216 cases of BA.2.74.

Besides India, the strain has also been reported by seven other countries: Japan (1), Germany (2), the United Kingdom (6), Canada (2), the United States (2), Australia (1), and New Zealand (2), as per data provided by Nextstrain.

Subvariant of concern?

An Indian genomic scientist has explained that the BA.2.75 variant includes new mutations in the spike protein, in addition to the mutations that are already present in the Omicron variant.

Of the mutations, ‘G446S’ and ‘R493Q’ are of particular concern, as it gives the variant the ability to evade several antibodies. This allows the variant to infect people who have been vaccinated, or have been infected previously.

Bloom Lab at the Fred Hutch research institute in the US, also flagged the subvariant, saying it was ‘worth tracking, as it has appreciable antigenic change relative to its parent BA.2″.

The lab 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.

Lipi Thukral, a scientist at the Council of Scientific and Industrial Research-Institute of Genomics and Integrative Biology (CSIR-IGIB) in Delhi told The Print, “This lineage may require urgent attention as most of the mutations are unique and [it] has also changed its physiochemical character quite a lot.”

Israeli medical expert Dr Shay Fleishon of the Central Virology Laboratory at Sheba Medical Center in Tel Hashomer noted that the rise seen in these sub-variants has been “at a level not seen in second-generation variants from other variants of concerns”.

Further, until now 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 second 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.

With inputs from agencies

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