The vaccines minister has declined to put a date on when all over-50s can expect to receive a Covid-19 jab but figures suggest late March may be an option if supplies continue.

Nadhim Zahawi said a target would be set for reaching all those aged 50 to 70, as well as those with underlying conditions which put them at higher risk of serious disease, once the most vulnerable have been offered a jab by February 15.

Previously, NHS England chief executive Sir Simon Stevens has said the aim is for all over-50s and those at risk to be vaccinated by the end of April.

But pressed on BBC Breakfast about when all over-50s and higher priority groups would be vaccinated, Mr Zahawi declined to set a firm date.

He said: “We will set out our target (for vaccinating groups 5-9) after we have hit our February 15 target.

“But you can do the maths. We did 600,000 in a single day – the deployment infrastructure that we’ve built can do as much vaccines as we get supply, so the limiting factor will be vaccine supply.

“You can see that in the next 10 or so days, we’ve got to do another almost touching five million and so if we keep that rate up, we will very quickly go down the list of the top nine.”

Asked whether that meant it would take another 35 days from February 15 to have jabbed all 31 million people in the first nine cohorts, Mr Zahawi replied: “That assumes the supply, so I don’t want to commit to a date without going through it with a very fine toothcomb with the whole team, because our limiting factor is the supply of vaccines ultimately.

“With any manufacturing process, especially one that is new, there are challenges around that, as we’ve seen in Europe and as we saw in the early days in the UK as well.”

On Radio 4’s Today programme, Mr Zahawi was asked whether his message to the country was that restrictions would not ease significantly until everyone over 50 is vaccinated.

He said: “The Prime Minister has made it very clear that on February 22, there will be a roadmap for how we intend to reopen the economy, beginning with schools on March 8, and then gradually, the rest of the economy.”

He said infection transmission studies among vaccinated care home residents and frontline health care workers would also provide more information on a “roadmap” for reopening and easing lockdown.

Slides presented by England’s chief medical officer, Professor Chris Whitty, at a Downing Street press conference on Wednesday suggested that around half of people who go into hospital with Covid-19 are aged over 70.

He said that after vaccinating the over-70s by February 15 “we would expect a situation where we can stop a very high proportion of the deaths but a rather smaller proportion of the pressure on the NHS – those very large numbers in hospital”.

This suggests that vaccinating people over 50 and the clinically vulnerable could be crucial for easing pressure on the NHS – cited as a major reason for ongoing restrictions.

Once the most vulnerable people, particularly those over 50 and those with chronic illnesses, are vaccinated then yes I think we can see a significant return to normality

Prof Whitty also told the briefing that offering every adult aged 18 and over a first dose by May and a second dose by August was “at the very optimistic end” of what was possible due to supply constraints.

On Thursday morning, Professor Andrew Hayward, a member of the Scientific Advisory Group for Emergencies (Sage), which advises ministers, told BBC Radio 4’s Today programme the country would be “more or less” back to normal for the summer.

“Once the most vulnerable people, particularly those over 50 and those with chronic illnesses, are vaccinated then yes I think we can see a significant return to normality,” he said.

“That in addition to the fact coronavirus is a seasonal disease, I think will make a big difference and allow us to open up.

“I think what we’ll see is a phased opening up as the vaccination levels increase, and then we will be more or less back to normal for the summer, I would imagine.”

Paul Hunter, professor of medicine at the University of East Anglia, said he believed people would be able to meet up with friends and family from March.

He told BBC Radio 4’s World At One he would like to see schools, and particularly junior schools, opening relatively soon.

Asked about when people could start to see friends and family, Prof Hunter replied: “Personally I believe we should be able to start doing that probably not long after (schools reopen) – if I had to bet on a time, I’d say some time in March certainly.”

On being allowed back into restaurants, he added: “I think that will be probably around the same time, maybe April. But again, it just depends what happens with the epidemic between now and then.”

Prof Hunter said on Wednesday that some form of social distancing may need to continue until spring 2022 even with effective vaccines.

He said measures would be needed through next winter to prevent a spike in deaths, largely among people who have not had a vaccine.

Meanwhile, the Government is facing pressure over a lack of detail on its plan for hotel quarantine for returning travellers.

Rules around international travel were tightened last month with the result that all travellers have to self-isolate for 10 days when they arrive in the UK.

The Government has also announced plans to make people quarantine in hotels following arrival from certain “high risk” countries, where new coronavirus variants have been identified.

Labour MP Yvette Cooper said it was troubling the Government had not yet spoken to major hotel chains about the plan.

“We’ve always been warned about both second waves and new variants; the work should have been done a long time ago,” the chairwoman of the Home Affairs Select Committee told BBC Radio 4’s Today programme.

“The problem is, of course, as long as we’re waiting, not just for this system but for stronger measures, we know that the system isn’t working at the moment.

“We can see that because the South Africa variant is spreading across the country, that’s the evidence that too many cases are getting into the country, then spreading in the country.”

But Mr Zahawi insisted that quarantine hotels are “part of a much bigger plan”, adding that Health Secretary Matt Hancock will be setting out details “in the next few days”.

Elsewhere, Switzerland has declined to sign-off the use of the Oxford University/AstraZeneca vaccine after countries including France said they would not recommend it for people aged 65 and over.

Dr Claus Bolte, head of authorisation at medicines regulator Swiss Medic, told the BBC his team were “not satisfied with the data we have received”.

Dr Bolte said the precise details of their concerns were confidential but said results of large-scale clinical trials in the US and South America using the Oxford vaccine would help to provide more sufficient data.