From 12% in early December, Omicron variant of SARS-CoV-2 turned into the dominant variant in circulation as 97% of samples sequenced during the last week of January in Tamil Nadu were of this variant.
According to data released by the Directorate of Public Health and Preventive Medicine on the proportion of Delta and Omicron variants in Whole Genome Sequencing (WGS) samples, 100% of samples were of Delta on December 4 and 7. Analysis found the Delta variant in 88% of samples and the Omicron variant in 12% of samples on December 11.
There was a quick shift in proportion on December 14, with 53% samples turning out to be of Delta and 47% of the Omicron variant. In a week, the percentage of the Omicron variant grew to 82% on December 21 but fell marginally to 63% on December 25. On December 31, 66% of samples were of the Omicron variant and 34% of Delta.
From the beginning of the year, Omicron turned out to be the dominant variant - 83% samples on January 1 and 80% on January 3. The Delta variant’s proportion dropped to 3% on January 26, while Omicron was detected in 97% of samples.
“The State strategically tests travellers returning from abroad, clusters, those in Intensive Care Units (ICU), persons fully vaccinated yet positive, breakthrough cases and any young person who dies, to know the prevalence of the COVID-19 variants through the WGS labs,” Health Secretary J. Radhakrishnan said.
T.S. Selvavinayagam, Director of Public Health and Preventive Medicine, said, “The latest WGS report that shows Omicron was present in 97% samples and the single-digit hospital occupancy rate indicates that as per the current scientific knowledge, we are moving towards a better situation.”
However, the DPH puts in a word of caution. “The caveat is that a new variant, which is transmissible like Omicron and severe like Delta will be a challenge, which may not happen considering the vaccine coverage in India and also across most parts of the globe. However, we still have memories of the Delta surge with people waiting for hospital admissions. So, we need to be cautious and follow COVID-19-appropriate behaviour,” he said.
