12 govt-owned labs in Tamil Nadu to test for Omicron variant

Samples of all international travelers who test positive for Covid-19 hereafter would be subjected to genomic sequencing

With Omicron being classified as a “variant of concern”, Tamil Nadu on Monday decided to use Thermo Fischer TaqPath Assay as a proxy test for the Omicron variant, pending sequencing confirmation, at 12 RT-PCR labs owned by the government.

In a circular, Director of Public Health (DPH) Dr T S Selva Vinayagam said samples of all international travelers who test positive for Covid-19 hereafter should be subjected to genomic sequencing at the State Public Health Laboratory here.

The DPH said the Thermo TaqPath RT-PCR test kits will be sent to 12 labs across the state, including five in Chennai, for testing the samples taken from international travelers and others. Two labs in Coimbatore, and one each in Tiruchirappalli, Salem, Madurai, Tuticorin and Kanyakumari will also test the samples.

The circular said S gene dropout or S gene target failure (SGTF) due to deletion at Spike position 69-70, like the detection of the Alpha variant, has been reported.

“Thermo Fischer TaqPath Assay can therefore be used as proxy test for this variant, pending sequencing confirmation. Use of the SGTF approach may lead to faster detection rates. Thermo TaqPath RT-PCR kits with S, N and ORF targets will be supplied to the govt RT-PCR Labs which has been prioritized based on their access to airport samples,” Dr Selva Vinayagam said.

Also read: States to increase vigil, testing for Covid-19 Omicron variant

It also said all inbound international travelers with symptoms of influenza-like Illness (ILI) will be screened for S gene drop out using the Thermo Taqpath RT-PCR kits.

The DPH also said any sample with S gene dropout or SGTF from a government or private RT-PCR lab in the recent past, preferably from October 15, should be referred to the State Public Health Laboratory for sequencing confirmation of the Omicron variant.

The circular also said the Thermo TaqPath RT-PCR kits will be used on samples taken from reinfection cases, vaccine breakthrough infections, community clusters, family clusters, and international travelers.

Also read: Sample of one person who came from South Africa is different from Delta, says Sudhakar

Health Minister Ma. Subramanian, who visited the State Public Health Laboratory established after the second wave of Covid-19 infections, said genomic sequencing of 469 samples so far have shown that over 95 per cent of the samples were infected with the Delta variant.

The circular came a day after the Health Department appointed nodal officers for all four airports that operate international flights to monitor international arrivals with airport authorities for prevention and control of the variant. The department had also asked district administrations to enhance Covid-19 surveillance, monitor and implement protocol for passengers travelling from the risk countries, and intensify the vaccination drive.

Tamil Nadu has so far administered nearly 7 crore vaccine doses and is fast-tracking vaccination by holding two special camps across the state every week. The state has also found that the death rate among the vaccinated population is very less, while it is quite high among the unvaccinated

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