S-gene drop: State lab begins whole genome sequencing

The State Public Health Laboratory (SPHL) will put out Omicron updates from Tuesday as about 150 samples will be processed within a duration of 4-5 days. The State Public Health Laboratory had received authorisation from the Indian SARS-CoV-2 Genomics Consortium (INSACOG) for conducting the whole genomic sequencing on Wednesday.

“The documentation process for sharing the sample reports with INSACOG and other formalities are under process parallelly and the sample collection has already begun. As the processing cycle takes about 4-5 days, it is expected that we should be able to share sample reports from next week,” said Health Secretary J Radhakrishnan. He added that the Delta variant is likely to be overshadowed by the Omicron variant as more cases of the variant are being reported in the State.

Currently, all the international passengers from at-risk countries and 10 per cent of those coming from nonrisk countries are tested for COVID-19 using RT-PCR, of which S-gene drop cases are subjected to whole genomic sequencing to detect the variant in the sample. The sources from the laboratory say that the whole genomic sequencing has been started for the samples that showed S-gene drop to detect them for Omicron for a single processing cycle of 150 samples.

Meanwhile, a senior official from the TN Health department said that the State will have to review if the whole genomic sequencing is required for all the samples as the Omicron variant becomes common, similar to the Delta variant.