On Wednesday, Professor Adam Finn, of the Joint Committee on Vaccination and Immunisation (JCVI), an independent expert advisory committee that advises health departments on immunisation, said modelling shows coronavirus cases will rise in the summer as lockdown is relaxed, Xinhua news agency reported.

"The models that we've seen on JCVI clearly point to a summer surge in cases as the lockdown is relaxed, because there are still many people in the adult population who've not been immunized," he told the BBC.

Finn, from the University of Bristol, said the UK is still "vulnerable" and the dates for easing restrictions may need adjusting.

"Quite a wide range of uncertainty" remains over how big the wave would be "because it depends on how quickly the vaccine rollout continues", he said.

It also depends on whether people will stick to the rules as lockdown is eased, he said.

"If people move too far forward with that too fast, we'll see things start to come up earlier," Finn said.

"The sense that the problem is all over, I'm afraid is a flawed one, we're still in a vulnerable situation, and there are still significant numbers of people who potentially could be harmed by this infection if this happens."

Prime Minister Boris Johnson said on Tuesday that as the UK continues to make progress in the fight against coronavirus, "we cannot delude ourselves" that the virus has gone away.

He noted that the majority of scientific experts are of the view that there will be another wave at some stage this year and Britons must learn to live with the virus.

However, he said there was nothing in scientific data to suggest the UK would have to deviate from the roadmap out of lockdown.

The UK has so far reported 4,411,068 confirmed coronavirus cases and 127,577 deaths.

More than 33 million people have been given the first jab of the coronavirus vaccine, according to the latest official figures.

Experts have warned that despite progress in vaccine rollout, the UK is "still not out of the woods" amid concerns over new variants, particularly those first emerged in South Africa, Brazil and India, and the third wave of pandemic on the European continent.