Know about Omicron's new sub-lineage BA.2 found in 80% of Kolkata samples

The newly-discovered infectious sub-variant of Omicron termed BA.2 has emerged as a dominant virus strain in European and Asian countries. This has also triggered fears regarding the future waves of the Covid-19 pandemic.

Britain has so far confirmed 426 cases of Omicron's new sub lineage BA.2 by conducting Whole Genome Sequencing (WGS). With 146 confirmed cases of BA.2, London has reported the highest number of Omicron subvariant in the UK, followed by the South East (97). The earliest case was reported on December 6, 2021

The UK Health Security Agency (UKHSA) designated the Omicron variant sub-lineage as a variant under investigation due to increasing numbers of BA.2 sequences both domestically and internationally. The latest variant has been detected in some 40 other countries, including most recent cases in India, Denmark and Sweden.

On the other hand, the INSACOG, in its latest bulletin, said while most Omicron cases in the country so far have been asymptomatic or mild, hospitalisations and ICU cases have increased in the current wave and the threat level remains unchanged.

BA.2 found in 80% of Kolkata samples

The sub-lineage of the Omicron variant was found in 80% of samples in Kolkata.

These samples were sent for genome sequencing between December 22 to 28.

Nearly 80% of them were found BA.2 positive with CT level below 30, indicating high viral load.

All positive samples with CT value under 30 were decided to be sent for genome-sequencing.

The decision to detect community transmission of Omicron was reversed as it became clear it had begun.

INSACOG officially confirmed the Omicron variant is in the community transmission stage in India.

BA.2 is in a substantial fraction and S gene dropout based screening is likely to give high false negatives.

S-gene drop-out is a genetic variation like that of new Covid-19 variant Omicron.