Chennai: The dominant variant of the coronavirus, Omicron, was found in more than 90 per cent of COVID samples drawn from patients between Dec 2021 and March 2023, a study by the directorate of public health has found.
After sequencing 11,526 clinical samples for analysis, scientists found 10,663 were omicron variants, according to a study published in the Journal of Medical Virology. “The variant is one of most versatile we have ever seen,” said one of the authors S Raju, who heads the state public health laboratory.
“We did detailed sequencing of 150 samples from the pool and documented 5009 mutations in the lab. That shows it has the potential to change so many times,” he said. Of the 10,663 samples, his laboratory conducted whole genome sequencing for 1,688 samples while the rest were sent to recognised labs in Pune and Bengaluru. The state lab documented severe illness to hospitalisation in 46.2 per cent of the cases. Of these, nearly 20 per cent succumbed to the disease.
While variants such as alpha (first wave) and delta (second wave) were quickly replaced, Omicron has managed to survive for more than three years. In TN, BA.5, BA.2 and XBB sub-linages of Omicron were the three most seen subvariants until JN.1 in December 2023.
The takeaway from the study, director of Public Health Dr T S Selvavinayagam said, was that the virus exists in the community. “It will keep modifying itself and may affect vulnerable populations. The elderly and people with comorbidities are at high risk,” he said.