The Omicron variant of the coronavirus disease is in the community transmission stage in India and has become the dominant strain in multiple metro cities where new cases have been rising exponentially, the Indian SARS-CoV-2 Genomics Consortium, the country’s genome sequencing body has said in its latest bulletin.

Community transmission happens when coronavirus cases reported in the last 14 days cannot be linked to a specific cluster and when there are multiple unrelated clusters of cases, according to the World Health Organization.

In its January 10 bulletin that was released on Sunday, the consortium also said that the BA.2, a sub-lineage of the Omicron variant, has been found in substantial fraction in the country and because of it S-gene dropout based testing was likely to give high false negatives.

The BA.2 sub-lineage is not detected in S-gene dropout test.

This testing method is used to detect the presence of Omicron variant as it cannot be detected by basic RT-PCR and RAT tests. When the S-gene dropout test detects the presence of other genes of the Sars-CoV-2 virus, but not the S-gene, it is considered indicative of Omicron infection.

According to the WHO’s guidelines, this testing is used as a proxy method to detect suspected Omicron cases, which are confirmed through genome sequencing.

In its bulletin, the consortium also said that while most Omicron cases have so far been asymptomatic or mild, hospitalisations and intensive care unit cases have been increasing in the current wave.

The genome sequencing body also said that the new variant, B.1.640.2, was being monitored.

“There is no evidence of rapid spread [of B.1.640.2] and while it has features of immune escape, it is currently not a variant of concern,” it added. “So far, no case detected in India.”

Globally, the consortium said, the rate of hospitalisation has been much lower in the Omicron wave as compared to the previous Delta wave. However, it said that the due to high number of cases, hospitalisations have been record high in many countries and putting a stress on the healthcare system.

“While deaths have been much lower during the new wave, compared to previous waves, there have been Omicron-associated deaths,” the consortium said. “In data so far, the majority of severe cases and deaths have been in unvaccinated subjects, with high protection associated with vaccination or previous infection.”

The highly transmissible Omicron variant has led to a huge surge in infections across the world. On Thursday, India had crossed the 3 lakh mark, recording 3,17,532 new coronavirus cases.

On Sunday morning, India recorded 3,33,533 new coronavirus infections taking the infection count in the country to 3,92,37,264 since the pandemic broke out in January 2020. The toll rose to 4,89,409 as 525 more people died due to the virus in the last 24 hours, government data showed.

On January 6, the WHO Director General Tedros Adhanom Ghebreyesus had warned against categorising the Omicron variant as “mild” even as it appeared to be less severe than the Delta strain of the disease.

While studies have concluded that the Omicron strain was less likely to cause severe disease than the Delta variant, scientists have also stressed that the new variant could spread faster due to a higher number of mutations and its ability to evade the immune response offered by vaccines.

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Omicron infections less severe than Delta, but not mild, says WHO