Health officials are monitoring whether a new strain of the Delta variant has emerged following Boardmasters festival.
The popular five-day music event in Newquay was attended by 53,000 revellers earlier this month and was followed by a sharp spike in Covid cases among young people.
An estimated 4,700 people caught the virus either from attending the festival or by coming into contact both someone who did, Cornwall Council said.
But there are concerns more people may have caught it there but as yet have not been officially traced back, as the Mirror reported yesterday.
A Public Health England scientist said while there is no evidence that the surge in cases linked to festivals relates to a new variant, "this will be continually monitored".
Have you caught Covid after attending a festival this summer? Let us know at webnews@mirror.co.uk
Dr Susan Hopkins, Covid-19 Strategic Response Director at PHE said: “There is no evidence to date that the surge in cases linked to festivals relates to a new variant or strain, but this will be continually monitored.
"We are consistently reviewing all sequencing data to monitor and assess the emergence of new variants and do this for any surge in cases.”
It comes after an unidentified senior official working on pandemic response in the south-west reportedly told the i newspaper what appears to be a fresh mutation is being referred to as the 'festival variant' by hospital staff in Cornwall and Devon.
Cornwall is now home to eight of the top 10 areas in England with the highest rates of infection.
While figures also show that more than half of the infections currently in the country are among those under the age of 30.
The highest rate of infection is now in the 10 to 19-year-old age bracket.
Cornwall Council said it "won't know the complete picture for another few days", in terms of more exact numbers for how many people caught the virus following Boardmasters.
Meanwhile, half a million people have been to the likes of Reading, Leeds and Let's Rock Scotland in Edinburgh in recent days.
Professor John Drury, of the government's Scientific Pandemic Insights Group on Behaviours, a sub-committee of Sage, has called for Downing Street to mandate festival organisers to implement stronger Covid-safe measures.
A spokesperson from Vision Nine - the company behind Boardmasters - previously told the Mirror it had "worked closely with experts" from Cornwall Council’s Public Health service, wider Cornwall Council departments, the NHS and emergency services "to put in place a variety of measures to manage the risk of infection at what is effectively a pop-up town with 50,000 temporary residents and visitors".
"In addition to having the advantage of perhaps the best ventilated venue in the country, we asked festival goers to play their part in reducing the impact of potential infection by showing proof of full vaccination, a negative lateral flow test or immunity from having had the virus before they could join us on site," they added.
