India on Wednesday reported 15 new cases of the new variant of the coronavirus, pushing the tally to 73, the health ministry said. The number of cases of the new strain, first discovered in the United Kingdom, was 58 till Tuesday.

“All these persons have been kept in single-room isolation in designated health care facilities by respective state governments,” the health ministry had said in a statement, released earlier in the day. “Their close contacts have also been put under quarantine. Comprehensive contact tracing has been initiated for co-travellers, family contacts and others. Genome sequencing on other specimens is going on.”

Genome sequencing can provide crucial information about how a virus is evolving or if new variants are emerging, how the virus is spreading from one place to another and whether cases in a given cluster are linked to one another.

From November 25 to December 23, 2020, about 33,000 passengers arrived at various airports in India from the UK. All of them are being tracked and tested via RT-PCR or reverse transcription polymerase chain reaction tests.

India suspended flight services from the UK on December 22 to contain the spread of the coronavirus. If the ban is not extended, the services will resume on January 8. The Centre has also issued guidelines for testing and surveillance of passengers arriving from the United Kingdom following the resumption of the flights.

The new virus strain

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, and 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 23 mutations in its genetic code – a relatively high number of changes compared with the version that originated in Wuhan, China, a year ago – and some of these are affecting its ability to spread. UK Prime Minister Boris Johnson has claimed that this was as much as 70% more transmissible than previous versions.

On Monday, Johnson announced a complete lockdown in England, fuelled by the new variant of the virus. The restrictions are due to last until at least mid-February. Johnson warned that the coming weeks would be the “hardest yet”.

Most scientists have said that the new variant has rapidly become the dominant strain in coronavirus cases in parts of southern England, and have linked it to an increase in hospitalisation rates. However, it is difficult to say exactly how much more transmissible the new variant may be as scientists have not yet done the kind of lab experiments that are required to assess it.

The new strain has also been reported in the United States, Denmark, Netherlands, Australia, Italy, Sweden, France, Spain, Switzerland, Germany, Canada, Japan, Lebanon and Singapore.