There are signs the UK is in the early stages of a third wave of coronavirus infections, a scientist advising the government has said.
Prof Ravi Gupta, from the University of Cambridge, said although new cases were “relatively low” the Indian variant had fuelled “exponential growth”.
He said ending Covid restrictions in England on 21 June should be postponed.
Environment Secretary George Eustice said the government could not rule out a delay to the planned lockdown easing.
On Sunday, the UK reported more than 3,000 new Covid infections for a fifth day in a row.
Prior to this, the UK had not surpassed that number since 12 April.
Prof Gupta told BBC Radio 4’s Today programme the UK was already in a third wave of infections and at least three-quarters of cases were the new (Indian) variant.
He said: “Of course the numbers of cases are relatively low at the moment – all waves start with low numbers of cases that grumble in the background and then become explosive, so the key here is that what we are seeing here is the signs of an early wave.”
However, he said the number of people who have been vaccinated in the UK meant this wave would probably take longer to emerge than previous ones.
“There may be a false sense of security for some time, and that’s our concern.”
Prof Gupta – a member of the government’s New and Emerging Respiratory Virus Threats Advisory Group (Nervtag) – said ending restrictions in June should be delayed “by a few weeks whilst we gather more intelligence”.
“If you look at the costs and benefits of getting it wrong, I think it is heavily in favour of delay, so I think that’s the key thing,” he added.
Another leading scientific adviser to the government, Prof Adam Finn, also urged caution over the 21 June date for easing restrictions.
“I think it’s unfortunate that everyone’s got this particular date in their head, because really what we need to do is understand how things are going and adjust accordingly,” he told ITV’s Good Morning Britain.
“This time around, we should be cautious, wait to see what’s happening, and then let everyone free, if you like, once we know for sure that that’s safe and that we can do that without having another round of lockdowns.”
The final stage of the government’s roadmap for lifting lockdown, which would remove all limits on how many people you can meet – either indoors or outdoors, is due no earlier than 21 June.
However, Mr Eustice told the BBC the government had to take things “one step at a time”.
“We can’t rule anything out. We know this has been a difficult pandemic, a dynamic situation. We have to make that judgment a couple of weeks before.
“It will only be by then that we will see the impact of the latest easement we made on 17 May.”
A final decision on whether restrictions will be lifted in England will be reached on 14 June.
The timetable for relaxing Covid measures varies across the UK. The Scottish government hopes to lift more restrictions on 7 June, while in Wales there is due to be a review on 3 June. In Northern Ireland some measures were relaxed on 24 May – the next review is due on 10 June.
Three weeks today has been dubbed Freedom Day by some – the point at which the remaining restrictions are due to be lifted in England.
But there’s increasing nervousness about whether it can go ahead in full because of the Indian variant.
And now you’re seeing some of the different pressures the government is going to have to weigh up.
Nervtag scientist Prof Ravi Gupta is urging minister to postpone 21 June by a few weeks to give more time for second vaccination doses to be done.
In the Telegraph, the British Chambers of Commerce warns the government against “rolling back on the roadmap” – saying it would be “astonishing” for the government to change tack.
And ministers? They say it’s too early to make a firm decision. They’re waiting for more data over the coming fortnight. Many will be watching to see what it says.
Trade body the Night Time Industries Association has previously warned any change to the government’s roadmap would wreak havoc on nightlife businesses.
Its chief executive, Michael Kill, said last week that thousands of businesses which have prepared for reopening “at considerable cost” risked being “plunged into further financial hardship” if re-opening did not go ahead.
The Indian variant – known as B.1.617.2 – is thought to spread more quickly than the Kent variant, which was responsible for the surge in cases in the UK over the winter.
In some areas of England – including in Bolton, Blackburn, and Sefton in north-west England and Bedford, Chelmsford and Canterbury in the South East – the Indian variant is causing the majority of infections.
Dr Helen Wall, senior responsible officer for the vaccine programme in Bolton, said the rise in cases in the town was slowing but there was no room for complacency.
She said many of the areas with the highest increases had very young populations, and getting more of those vaccinated would help tackle the rise.
“I think the age of (vaccine) eligibility going down every few days has really helped, and will really help us, if we can get those people through the doors to be vaccinated asap,” she said.
In England, people aged over 30 are currently able to book to get the vaccine.
In other developments:
Tighter rules for travellers from the UK have come into force in France in response to the spread of the Indian variant, meaning only EU nationals, French residents, or those travelling for essential reasons can enter
Scotland’s Health Secretary Humza Yousaf has warned restrictions may not be relaxed further next week in parts of Scotland where infections are rising
Holiday let firms in Wales are predicting a bumper summer as they are “blown away by demand” for bookings
And the UK economy’s recovery from the pandemic is set to be stronger than previously thought, the Organisation for Economic Co-operation and Development has suggested