Health dept to conduct S-gene target failure test to detect Omicron cases

KOLKATA: State Health department decided to conduct S-gene target failure test, a primary screening method to find out the presence of Omicron variant in Covid infected patients. It will give an idea to the health professionals if someone is Omicron positive even without genome sequencing.

A senior health official said as people are coming to our state from foreign countries in large numbers, most of them are testing negative for Covid. However, there is a chance of new variants being transmitted to other patients. The number of Omicron infected people in Bengal has also reached four. The number may go up in the future. As a result, it would be extremely beneficial if the Omicron positives are found within a short span of time and segregations can be done. It takes a couple of days to get a genome sequencing report of a sample.

"Mutation in Omicron has happened in the S-gene and a sample positive for this variant will have the S-gene missing. WHO had also suggested that countries using PCR test can apply the S-gene target failure, which will indicate if someone is infected with Omicron. The report will further be corroborated with the report of genome sequencing," said the official.

'S-gene target failure test'—which will bring the results faster— will be introduced in the city's hospitals and the facilities will also be taken to the districts later. Health department has already decided to conduct genome sequencing on those whose viral loads or Ct value is below 30. Genome sequencing is mandatorily performed on foreign returnees who test positive for Covid on their arrival at the Calcutta airport.

Health experts have however said there was nothing to worry as the Omicron infected patients were recovering fast. "As a considerable number of people in the country have already been infected with Covid, a majority of the people have already developed hard immunity. As a result, changes in the Covid variants will gradually hardly have any fatal impact on patients. There is nothing to panic about Omicron. Omicron patients are recovering within a short time,"said Prof Dr Uchhal Kumar Bhadra, former principal of Beliaghata ID Hospital.

It may be mentioned here that the ICMR-approved RT-PCR kits are used by most labs across the country and they do not include the S-gene. These RT-PCR kits mostly target two genes – N and ORF — not the S-gene. RT-PCR kits do not target the S-gene, and hence it will not throw any indication of which variant has caused the infection, said Dr G Mukherjee, a senior pathologist in the city.