Omicron strain in community transmission stage in India, dominant in multiple metros: INSACOG

Omicron is in community transmission in India and has become the dominant variant in multiple metros, Insacog, the genomic consortium has said.

In its latest weekly newsletter, Insacog cautioned that the threat level remains "unchanged" asserting that most Omicron cases so far have been asymptomatic or mild though hospitalisations and ICU cases have been increasing in the current wave.

As reported by ET last week, in the fourth week of December, Omicron was found in 50% of the samples sent for genomic sequencing. In the second and third week of January, it is around 90-95%.

The Insacog genomic surveillance data showed that Omicron has been found in 100% of cases in Rajasthan, followed by 90% in Delhi, 80% in Maharashtra. Insacog expects that the spread of Omicron in India is through internal transmission and not on account of those who have travelled overseas.

Insacog said that a revised sampling and sequencing strategy is being worked out to address genomic surveillance objectives in the wake of a dynamic changing scenario.

Experts say that the situation requires constant vigil. "Since initial detection has primarily been in vaccinated travellers, this should not be taken to mean that Omicron infection will also be mild in high-risk unvaccinated subjects.

The threat level remains high and requires constant vigil as the situation rapidly evolves with community spread. Covid-appropriate behaviour and vaccination are the main shields against all mutations of SARSCoV-2 virus," it said.

According to experts, BA.2 lineage is a substantial fraction in India and S-gene dropout-based screening is thus likely to give high false negatives. This means that in some cases the RTPCR test may show false negatives.