A traveller who had returned from Nigeria, a non-risk country, tested positive for COVID-19, and the S-gene dropout was observed in the preliminary analysis of his sample, raising suspicion that he could have the Omicron variant of the novel coronavirus, Health Minister Ma. Subramanian said on Tuesday.
Six of his family members have also been tested and the samples sent for genome sequencing. He returned two or three days ago, and was randomly tested on arrival at the Chennai international airport.
Currently, 2% of the travellers from the non-risk countries were randomly tested. In compliance with the guidelines for travellers from the non-risk countries, he was allowed to go home after his sample was lifted. As the result returned positive for COVID-19, he was picked up in three hours, health officials said.
Later, six of his family members, who had mild symptoms, were found to be COVID-19-positive. All seven samples were sequenced at the State Public Health Laboratory’s genome sequencing facility during which the S-gene dropout was observed. “All of them were admitted to Government Corona Hospital, Guindy, and are under intense monitoring. They have cold, cough and mild body ache,†the Minister told reporters at the Chennai airport.
The Health Department has asked the Institute for Stem Cell Science and Regenerative Medicine (InStem), Bengaluru, to expedite the genomic sequencing of seven samples in which the S-gene dropout was observed, he said.
So far, 37 samples were sent to InStem for whole genome sequencing to identify the SARS-CoV-2 variant. Of them, four have returned positive for the Delta variant, and the results of 33 samples were awaited. “We have asked InStem to expedite the sequencing of the seven samples as preliminary analysis has raised the suspicion that it could be the Omicron variant. We expect the results by tomorrow,†he added.
Explaining the S-gene dropout, Health Secretary J. Radhakrishnan said maximum mutations occurred in the spike protein. “The World Health Organisation has said this will not be detected. This could be an initial marker for the variant. We have 3.5 lakh kits to detect the S-gene dropout,†he said.
The Minister said 2% of the travellers from non-risk countries were tested on any variation in temperature at mass fever screening at the airports.
Until Tuesday morning, 11,481 persons, who travelled from countries at risk, were tested. Of the 58,475 persons who travelled from the non-risk countries, 1,699 were randomly tested. “So far, 37 persons were found positive for COVID-19. Report from InStem confirmed that four of them were positive for the Delta variant. The remaining 33 persons are in hospital isolation in Chennai, Tiruchi and Nagercoil,†he said.
The Minister added that surveillance would be stepped up for persons travelling by train and road. Persons travelling from Kerala by road were screened in 13 border areas, while those from Karnataka were screened at Hosur. Fever screening would also be intensified.
Dr. Radhakrishnan said cluster surveillance was key at this point. “This is not the time to panic but to understand that we need to go back to the basics of masking and physical distancing. Those who have symptoms should get tested and isolate themselves till the results arrive. People need to be careful while at gatherings and at places of common dining,†he said.
T.S. Selvavinayagam, Director of Public Health and Preventive Medicine, and K. Narayanasamy, director of Government Corona Hospital, were present.