The job of the Covid-19 vaccination programme is not yet “done”, an immunisation expert has said as scientists are split on whether the Government should press ahead with the final stages of easing social restrictions later this month.

Professor Adam Finn, of the Joint Committee on Vaccination and Immunisation (JCVI), said there are still many people who are vulnerable to the effects of Covid-19 as he warned “the idea that somehow the job is done is wrong”.

Experts are divided over whether the final stage of easing social restrictions should press ahead on June 21 amid a surge in cases of the new variant first identified in India.

Downing Street has indicated that Boris Johnson still sees nothing in the data to suggest the plan to end all legal lockdown restrictions on June 21 will need to be delayed.

Asked about the Prime Minister’s plans amid warnings over the spread of the Indian variant, a No 10 spokesman said: “The Prime Minister has said on a number of occasions that we haven’t seen anything in the data but we will continue to look at the data, we will continue to look at the latest scientific evidence as we move through June towards June 21.”

Prof Finn, from the University of Bristol, told BBC Radio 4’s Today programme: “There’s vulnerability across the country. The idea that somehow the job is done is wrong.

“We’ve still got a lot of people out there who’ve neither had this virus … nor yet been immunised, and that’s why we’re in a vulnerable position right now.”

He told LBC that pressing ahead with the easing of restrictions on June 21 “may be a bad decision”.

Professor Ravi Gupta, a member of the New and Emerging Respiratory Virus Threats Advisory Group (Nervtag), said a delay of a few weeks could have a significant impact on Britain’s battle against the pandemic and recommended it should be made clear to the public that it would be a temporary measure based on the surge in cases of the new variant.

“Even a month delay could have a big impact on the eventual outcome of this,” Prof Gupta told ITV’s Good Morning Britain.

Pat Cullen, acting general secretary and chief executive of the Royal College of Nursing, urged ministers to watch the data, adding: “As the NHS starts the road to recovery now is the time to take cautious steps and not take an unchecked leap to freedom.”

However, Robert Dingwall, professor of sociology at Nottingham Trent University, said it was important to press ahead with the June 21 easing from a societal point of view.

He told Times Radio: “I personally don’t see any case for delay … from a societal point of view, I think it’s really important that we go ahead on June 21 and I’ve not really seen anything in the data that would lead me to doubt that as a proposition on the evidence to date.

“I think we need to recognise the way in which levels of fear and anxiety in the population have been amplified over the last 15 months or so.

“We’ve got to look at the collateral damage in terms of untreated cancers, untreated heart conditions, all of the other things that people suffer from.

“We’ve got to think about the impact of economic damage that would be caused by further periods of delay and uncertainty.

“What we see at the moment, I think, is really a preview of what it means to live with Covid as an endemic infection – these waves will come, they will pass through; there will be high levels of mild infections in the community for periods of time, a handful of people may be seriously ill, even fewer may die.

“But that’s what happens with respiratory viruses and we’ve lived with 30-odd respiratory viruses for since forever.”

He added: “By the time we get to June 21, everybody who is in the nine priority groups or the highest risk will have had both jabs and would have had a period of time to consolidate the immunity.

“What are we going on with is really running into younger age groups who are intrinsically much lower risk. Many of the scientists who’ve been talking over the weekend simply haven’t adjusted their expectations to understand that – (for these people) Covid is a mild illness in the community.”

The Government’s former chief scientific adviser said ministers need more data before they can make a final decision.

“We need to substitute speculation for scientific data that’s the truth of the matter, as everyone has said in the last few days, the situation is very delicately balanced with some three sets of moving parts,” Professor Sir Mark Walport told BBC Breakfast.

“Firstly, we have got a new more transmissible variant, of that there is no doubt, though we don’t know exactly how much more transmissible.

“Secondly, there’s been a change in behaviour following the relaxation of measures on May 17 and the effects of that will just be starting to come through.

“Thirdly, we’ve got a vaccination programme that is very successful, but with a lot of people that still need both their second dose of vaccine and vaccination from scratch.

“I’m afraid that weeks before the Prime Minister has to make the difficult decision it is going to be necessary to bring in the data.”

Asked if the nation is in the foothills of another wave, he added: “I hope not, but it’s not impossible.”

In Scotland, First Minister Nicola Sturgeon will confirm “whether and to what extent” plans to further ease coronavirus restrictions can take place on June 7, amid extra controls in Glasgow to deal with rising cases.

The race to vaccinate the UK gathered pace on Monday after a major walk-in vaccination centre at Twickenham Stadium opened up the jab offer to anyone aged over 18 in order not to waste doses. Currently, only those aged over 30 in England are being invited to book their first vaccine.

The call led to lengthy queues in south-west London as thousands of young people lined up for a jab, adding to the 39.3 million people in the UK who have been given a first dose and a further 25.5 million who have had both.

Across the UK almost three-quarters (74.8%) of the adult population has had their first Covid jab, with almost half (48.5%) having had their second.

On Monday, 3,383 lab-confirmed cases were confirmed in the UK – the sixth day in a row that 3,000 or more cases had been recorded.

One further death was reported within 28 days of a positive coronavirus test, according to Government data.

It comes as the EU’s ambassador to the UK has raised hopes that those wanting to holiday in Europe later this summer will find the process easier.

Joao Vale de Almeida told BBC Radio 4’s Today programme: “I hope many, many British citizens will come to our countries and I hope many EU citizens will visit the UK.”

He said the bloc was hoping a digital Covid certificate would pave the way for greater ability to travel.

“We’re hopeful that some time later in the summer, around July, we could be in a situation where travel and tourism will be made a lot easier,” he added.

It comes as new data from the Office for National Statistics show a steep rise in healthcare expenditure as a result of the pandemic.

The ONS said current healthcare expenditure in 2020 is estimated at £269 billion, a cash increase of 20% on 2019 – the largest increase on record back to 1997.

The share of GDP attributed to healthcare rose to about 12.8% in 2020, up from 10.2% in 2019.

Jonathan Athow, deputy national statistician for economic statistics for the ONS, said: “The unprecedented effects of the pandemic have seen spending on health rise at a rate not seen in modern times.”

Meanwhile, schools could stay open half an hour longer each day as part of a £15 billion plan to help pupils catch up after having their learning disrupted by coronavirus shutdowns, according to the Times.

And the UK Government may follow the World Health Organisation’s (WHO) suggestion on naming Covid-19 variants.

The WHO said variants of concern should be named after the Greek alphabet to avoid using terms like the “Indian variant” or the “South African variant”, which can lead to stigma.

The variant first identified in Kent would thus be named the Alpha variant and the variant first identified in India is called Delta, according to WHO.

Asked if the Government will follow the WHO in using Greek letters to describe new coronavirus variants, business minister Paul Scully told LBC radio: “I don’t think it matters either way, frankly, but I think we will be calling it Alpha, which is the Kent variant, and Delta which is the variation that started in India.

“That’s not my decision but I suspect that will be the case.”