The coronavirus variant that first emerged in India is now being transmitted within the UK after three cases were detected that were not associated with travel.
The variant, known as B.1.617.1, has a double mutation of the spike protein, prompting fears that vaccines are less effective in preventing it.
And a new report from Public Health England (PHE) revealed that of the 132 cases now recorded in the UK, three were among people who were not believed to have contracted it while travelling.
This would mean the infections were contracted in Britain, and that the coronavirus variant is now being transmitted within the country’s borders.
Dr Julian Tang, consultant virologist at the Leicester Royal Infirmary and Honorary Associate Professor in the Department of Respiratory Sciences, told Sky News the development was "not surprising".
"By the time you find one of these cases, there may well be between five or 10 of them incubating," he said.
"Trying to chase this virus in any shape or form is relatively futile.
"We saw with the South African variant that it went from a couple of hundred to over 500 fairly quickly, and we can expect this to follow the same pattern."
He said the variant’s double mutation "suggests it can well escape vaccine protection".
"However, background protection from the vaccines overall will probably mean they protect against severe disease and death, although we may continue to see transmission from variants like this for some time," he said.
He added that there was currently no evidence that the Indian variant was associated with increased severity of disease.
"I don’t think we need to be especially worried about this news unless we begin to see evidence of increased severity, or that it can escape the vaccine protection against severe disease and death, which we haven’t seen yet," he said.
"We’re not going to see massive surge in new cases and deaths due to this."
The PHE report said the three cases not associated with travel were detected on 24 March, 27 March and 8 April.
Meanwhile, the report also revealed that there were now a total of 592 confirmed cases in the UK of the B.1.351 variant that first emerged in South Africa, and which is also believed to evade vaccines.
Of those infections, 154 had no travel link.