- December 9, Abu Dhabi: Covid negative
- December 11, Hyderabad: Covid positive. Subsequently found positive for Omicron
- December 12, Malda: Covid negative
- December 15, Malda: Covid negative
The 7-year-old boy who arrived in Malda from Abu Dhabi, via Hyderabad, on Saturday has tested positive for Covid once and negative thrice within a span of seven days.
Doctors said one plausible explanation for this could be that the child had contracted Covid some time ago and the test in Hyderabad detected the presence of the old virus in the sample.
The boy had given his samples for a Covid test on December 9 before flying out of Abu Dhabi, in the UAE, with his parents and elder sister. The test returned negative, according to his travel documents.
He was tested for Covid again on his arrival at the Hyderabad airport on December 11.
The test came back positive and genome sequencing of his sample revealed he had been infected with the Omicron variant of the coronavirus, which was first detected in South Africa last month and is spreading rapidly in many countries around the world.
According to the testing protocol announced by the Centre, all passengers arriving from countries identified as ‘at-risk’ for the spread of Omicron have to take the Covid test at the point of entry.
Two per cent of the passengers from other countries, selected randomly by the airlines concerned, have to take the test.
The UAE is not among the at-risk countries.
The boy again gave his samples on December 12 after arriving in Malda district of Bengal. “We are not sure why the boy’s family got him tested in Malda,” an official of the district’s health administration said.
On Thursday, the state health department collected the child’s samples for yet another test after learning that he had been infected with Omicron.
Thursday’s test as well as the one on December 12 came back negative.
“It could be that the Ct value of the test conducted in Hyderabad was very high, which means the viral load was low. A high Ct value could mean that he was infected some time back. It was an old infection,” said Chandramouli Bhattacharya, an infectious diseases expert at Peerless Hospital in Kolkata.
Bhattacharya said it was plausible that the test in Hyderabad identified dead viruses that were still present in the boy’s upper respiratory tract.
Health officials have not revealed the Ct value in the Hyderabad report.
“Samples from the upper respiratory tract are taken for the Covid RT-PCR test. The virus enters the lining cells in the upper respiratory tract. These lining cells are renewed every three months. So it is possible that the viruses had died but were still in the lining cells. It could be that the test identified these dead viruses and gave a Covid positive report,” said Bhattacharya.
But, he added, one should also keep in mind that the Omicron variant was first detected only recently.
Ajay Chakraborty, the director of state health services, said the child’s parents, sister and grandmother, too, tested negative.
“The child, his parents and his sister were admitted to the Malda Medical College and Hospital on Thursday. All of them were discharged today after they tested negative,” an official of the hospital said.
“The boy has been discharged following the norm since he tested negative in two successive tests. He is now eligible for home quarantine for a week,” said Chakraborty.
Omicron negative
The genome sequencing of the sample of a man in his 70s who tested positive for Covid on Saturday after arriving from Bangladesh revealed that he had not been infected by Omicron. The genome sequencing report arrived on Thursday.
“A sublineage of the Delta variant was found in his sample,” Chakraborty said.