Omicron in community transmission stage in India, dominant in multiple metros, says INSACOG

The Omicron variant of Covid has reached community transmission level, says the Indian Consortium on Genomics that goes by the acronym INSACOG.

This essentially means that further spread of Omicron in India is now expected to be through internal transmission, not foreign travellers. A revised sampling and sequencing strategy is therefore being worked out to help understand how the variant spreads and evolves, and to suggest the best possible public health response.

"Omicron is in community transmission stage and has become dominant in multiple metros like Mumbai and Delhi, where cases have been rising exponentially", said the consortium in its recent bulletin published on Sunday.

The INSACOG conducts genomic surveillance across the country through sequencing of samples from Sentinel sites; it also conducts detailed district-wise analysis for some states. (A total of 1,50,710 samples have been sequenced and 1, 27,697 samples have been analysed so far by INSACOG.)

The research body has made another interesting finding -- that an infectious sub-variant of Omicron BA.2 lineage has been detected in a considerable fraction in India.

"BA.2 lineage is in a substantial fraction in India; therefore, S-gene dropout-based screening is likely to give high false negatives. (S-gene drop-out is a genetic variation like that of Omicron.)

The consortium has further said that while most Omicron cases so far have been asymptomatic or mild, hospitalizations and ICU cases have been increasing in the current wave. The threat level remains unchanged.

"The recently reported B.1.640.2 lineage is being monitored. There is no evidence of rapid spread and while it has features of immune escape, it is currently not a variant of concern. So far, no case detected in India", the bulletin reads further.

At global level, most severe cases and deaths have been in unvaccinated subjects, the study adds.