New Delhi | Jagran News Desk: The Omicron variant of COVID-19, which was detected first in South Africa in November, has started replacing the Delta strain in India in "terms of number of cases", reported news agency ANI quoting official sources. The Delta strain had caused the second wave of the pandemic in the country.

Dubbed as a 'variant of concern' by the World Health Organisation (WHO), Omicron has ravaged the United States of America and most of Europe, including the United Kingdom (UK) and France. In India, it has infected over 1,200 people across 23 states and union territories (UT) till now. Maharashtra is the worst-hit state with 450 Omicron cases, followed by Delhi (320), Kerala (109) and Gujarat (97).

Experts have also warned that Omicron, which is supposedly a more contagious variant, will replace Delta over the coming weeks as the dominant global strain. "From current data, it looks like Delta will go down over time relative to Omicron," said Dr Sebastian Maurer-Stroh, executive director of the state-owned Agency for Science, Technology and Research's Bioinformatics Institute.

The new variant was first detected in South Africa on November 11, and then in Botswana and Hong Kong, before it rippled across more than 110 countries, as at last weekend.

Omicron is already dominant in Australia, Russia, South Africa and the United Kingdom, noted Professor Dale Fisher, a senior consultant at the National University Hospital's Division of Infectious Diseases.

"We are seeing a global transition from Delta to Omicron because with a greater transmissibility, the virus is fitter and has a reproductive advantage," said Dale Fisher.

But he added a caveat that the reports of Omicron rates may be biased as some countries do little gene sequencing, and those that do may be looking for deletion in a specific spike gene to identify Omicron, instead of carrying out whole-genome sequencing.

Dale Fisher said most experts in the field believe Omicron will replace Delta as the dominant strain. While the Delta variant has 13 mutations with nine on the spike protein, Omicron has about 50 mutations not seen together before, and 32 of them are on the spike protein.

Because of its mutations, the Delta variant attaches more effectively to human cell receptors, causing it to be more infective, said Fisher. But the Omicron variant made health authorities more concerned as the virus is even "stickier" because of its extra mutations, he added.

The rise and fall of new variants over time follows the laws of nature and the survival of the fittest, Dale Fisher noted.

Dr Maurer-Stroh said the environment in which two variants compete will also help determine which is more successful. "As immunity in the population increases from both vaccination and natural infection, severity goes down but even slightly better escape from the prevalent immune response can give one variant the extra edge over another," he said.

"This is also what we see with different flu variants every year." Dr Maurer-Stroh said. "Because of the great benefit of vaccination including boosters, we see less severe cases."

As Omicron and Delta continue to wrestle for dominance, some have wondered whether it would be possible to be infected with both strains at the same time. "This is possible but rare. And very quickly, only one variant would be the dominant infection in the body," added Dr Maurer-Stroh.

International evidence indicates that the Omicron variant is likely to be more transmissible, but less severe than the Delta variant.

(With inputs from agencies)

Posted By: Aalok Sensharma