New Delta mutation AY.4 dominant in Karnataka: Scientists

A sublineage of the Delta variant known as AY.4 has been found to be the dominant variant in Karnataka among Covid-19 samples sequenced in June and July, with researchers noting that the variant had mutated further and reentered the country.

Among the 523 sequences studied, AY.4 was found in 41.1% of them (215), overtaking even the baseline Delta (210 sequences 40.2%) that was responsible for the deadly second wave in the state. The next highest was the AY.12 variant (72 sequences 13.8%).

Genomic scientists said AY.4 is mostly from the UK while AY.12 is from Israel, where cases are rising despite 60% of its population being fully vaccinated.

The sequencing was done by labs part of INSACOG (Indian SARS-CoV-2 Consortium on Genomics) and uploaded to GISAID, an open access genomic database of influenza viruses.

Associate Dean of HCG Centre for Academics and Research Dr Vishal Rao, who is also a member of the State Covid-19 Genomic Surveillance Committee, said, "GISAID data indicates Delta sublineage B.1.617.2.4 or AY.4 is on the rise and is the dominant variant in Karnataka now. It is being studied across the world. The Delta variant has 13 mutations and AY.4 is one of them."

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The committee has proposed studying its link to breakthrough infections, hospitalisations and deaths.

When researchers studied the changes between the last few months and now, they found that just 11% (78) of the 715 sequences in Karnataka had AY.4 in March-April.

"AY.4 is rising in the US, Israel and India, specifically in Karnataka," Rao cautioned.

"When we compared Kerala and Karnataka, it was in the latter that it had increased in the last two months. In Kerala, baseline Delta is dominant."

According to Rao, this meant that "certain states can see a rise in specific mutations".

"This has implications with regard to vaccine-escape mutations, breakthrough infections and also hospitalised patients. We're hoping to correlate this with seroprevalence and R0 (reproductive number). The UK is already undertaking research on this," Rao added.

Researchers are hoping that the genomic sequencing results of around 300 hospitalised Covid patients in the state, which could be available by Saturday, to shed light on the emerging dominant variants in them.

Amid the development, State Health Commissioner Dr Trilok Chandra said travellers coming from the US should compulsorily have a negative RT-PCR certificate done within the last 72 hours before boarding.

"All travellers shall upload the certificate in the Air Suvidha portal. Only then, the airlines will allow them to board the flight," he said.