At least 22 people have tested positive for Covid-19 in India after returning from the United Kingdom, where a new coronavirus variant that is potentially more infectious has emerged, NDTV reported on Thursday.

Of these, 11 tested positive in Delhi, eight in Amritsar, two in Kolkata and one in Chennai. Five tested positive for the coronavirus in Delhi on Tuesday, while six others were found to be infected the next day, according to the Hindustan Times.

Gauri Agarwal, founder of the Genestrings Diagnostic Center which is responsible for coronavirus testing of all passengers at the Delhi airport, said that the 11 passengers were on four flights from London, according to PTI. “Testing was done comprehensively, as directed, irrespective of any existing reports or exemptions,” she said. “A total of 950+ inbound passengers from London were tested at our lab at T3 terminal, Indira Gandhi International Airport and 11 of them tested positive.”

She added that the positive samples have been sent to National Centre for Disease Control in Delhi for further research using genome sequencing. “We do not know yet if any of these positive cases are infected with the new UK strain,” Agarwal added.

On Tuesday, the health ministry issued a standard operating procedure for people coming to India from the UK amid alarm about the rapidly spreading strain of coronavirus that has caused cases to increase there. This includes mandatory RT-PCR or reverse transcription polymerase chain reaction tests on arrival and isolation in a separate institutional facility for positive cases. If fliers from UK test positive on arrival, then passengers sitting in the same row, three rows ahead and three rows behind will also be put under institutional quarantine.

Since this order, a total of four UK flights have landed in Delhi and 50 passengers are under quarantine. “Our understanding is that the health ministry may have given directive to ensure proper contact tracing to authorities at the airport, and hence passengers sitting in the same row or nearby rows on the flight might have been asked to be quarantined,” Agarwal said.

More than 50 countries, including India, have imposed travel restrictions on the UK. India has suspended flights from the UK till December 31. With the Centre’s new guidelines, several hundred passengers were tested at various airports in India. The process has led to chaos and confusion, including in Delhi, Mumbai and Kolkata airports.

Meanwhile, in Punjab’s Amritsar, seven passengers and a crew member on board Air India’s flight from London’s Heathrow airport tested positive, according to The Times of India. Assistant Deputy Commissioner Himanshu Aggarwal said all of them will be sent a hospital of their choice after counselling.

Kolkata Health Secretary NS Nigam said the two passengers from London who tested positive in the city have been admitted to hospitals. “Experts are analysing their samples to see if it is the new strain,” he added.

In Chennai, the state government said it will send samples of the man who tested positive to the National Institute of Virology in Pune for analysis, Deccan Herald reported. “Once he tested positive, he was shifted to King’s Institute for further treatment,” Principal Secretary (Health) J Radhakrishnan told reporters. “All passengers who came from the UK are being monitored.”

The new variant

The new UK virus variant, which scientists have named “VUI – 202012/01”, includes a genetic mutation in the “spike” protein, which could result in coronavirus spreading more easily between people. It was first announced by Matt Hancock, the UK health secretary, on December 14. It was subsequently confirmed by Public Health England and the UK’s Covid-19 sequencing consortium. Screening back through databases of SARS-CoV-2, the virus which causes Covid-19, the first sample was taken in the county of Kent on September 20.

The variant carries 14 defining mutations including seven in the spike protein, which mediates entry of the virus into human cells. This is a relatively large number of changes compared to the many variants in circulation globally. Prime Minister Boris Johnson has claimed that this was as much as 70% more transmissible than previous versions. But there is currently no evidence that the variant is more likely to cause severe coronavirus infections or that it would render vaccines less effective.

The World Health Organization also on Monday tried to allay the concerns and said the strain could be controlled using existing measures.