The UK is unlikely to achieve herd immunity through a Covid-19 vaccination programme before the summer, a scientist advising the Government has said.

Calum Semple, professor of outbreak medicine at the University of Liverpool and a member of the Scientific Advisory Group for Emergencies (Sage), described the Oxford/AstraZeneca vaccine as a “game changer” if it is approved by the Medicines and Healthcare products Regulatory Agency (MHRA) in the coming days.

But he told BBC Breakfast: “To get the wider community herd immunity from vaccination rather than through natural infection will take probably 70% to 80% of the population to be vaccinated, and that, I’m afraid, is going to take us right into the summer I expect.”

It comes as hospitals in the South face a rise in pressure as the number of coronavirus patients receiving treatment heads towards the April peak.

Saffron Cordery, deputy chief executive of NHS Providers, said: “We know that the rate of Covid-19 admissions is rising and some trusts are reporting up to three times the number of Covid patients than at the peak of the first wave.

“This means hospitals and also ambulance services in Tier 4 areas and beyond are incredibly busy, compounded by increasing staff absences due to illness and the need to self-isolate.”

She added: “Nightingale hospitals were created as an insurance policy. It is possible that they will be used in the near future.

“However, they will need additional staff, which is a resource currently in short supply.”

Paramedics in the capital are receiving almost 8,000 callouts daily, and Boxing Day was described as one of London Ambulance Service’s “busiest ever days”.

The 7,918 calls received by London Ambulance Service (LAS) on December 26 was up more than 2,500 on the 5,217 received on the same day last year, and medics are receiving support from other ambulance services in the South.

Dr Katherine Henderson, the president of the Royal College of Emergency Medicine, described her experience of working in a hospital on Christmas Day as one of “wall to wall Covid”.

“We see patients who are coming in who have Covid symptoms and then we have other people coming in with other symptoms who turn out to be Covid positive.

“Between that, there’s a great deal of difficulty getting those patients through into the wards,” she told BBC Breakfast.

“The chances are that we will cope but we cope at a cost – the cost is not doing what we had hoped, which is being able to keep non-Covid activities going.

“So we will stretch staff, the problem is at the moment we have a lot of staff sickness.”

Professor Jackie Taylor, president of the Royal College of Physicians and Surgeons of Glasgow, told the programme London and the South East are now experiencing what Scotland went through in the autumn.

“We are still seeing significant amounts of patients with Covid and large amounts of standard respiratory infections and other emergency that we see at this time of year that mount up to a standard winter pressure,” she said.

The Government said a further 316 people had died within 28 days of testing positive for Covid-19 as of Sunday, bringing the UK total to 70,752, with a further 30,501 lab-confirmed cases of coronavirus.

But the figures for deaths and cases are likely to be higher as Scotland is not releasing death data between December 24 and 28, and Northern Ireland is not providing either case or death data over the same period.

According to the Government’s Covid dashboard, there were 21,286 people in hospital with coronavirus across the UK on December 22, which is the last day for which data is available.

This is slightly less than the 21,683 patients recorded on April 12.

Infection rates in England are currently highest in areas of Essex, London and other parts of the South East.

Brentwood in Essex has the highest rate in England, with 1,111 new cases recorded in the seven days to December 23 – the equivalent of 1,442.5 cases per 100,000 people.

The area is in Tier 4 of Covid-19 restrictions along with most of the south of the country, with socialising banned and people told to stay home.

A review which will decide whether more areas will be moved into the harshest tier is expected on December 30, as the new highly infectious variant of coronavirus spreads across the UK and the world.

More than six million people in east and south-east England went into the highest level of restrictions on Saturday, which now affects 24 million people representing 43% of the population.

And Cabinet Office Minister Michael Gove has not ruled out the whole country being moved into Tier 4 restrictions.

He told BBC Breakfast: “We review which tiers parts of the country should be in on the basis of scientific evidence.

“The Joint Biosecurity Centre (JBC) will be making a recommendation to ministers, but I can’t pre-empt that because it obviously has to be a judgment based on the medical situation.

“But as you quite rightly point out the NHS is under pressure and these are difficult months ahead.”

Lockdown measures are also in place across the other three home nations, after mainland Scotland entered Level 4 restrictions from Saturday for three weeks, and a similar stay-at-home order is also in place in Wales.

Northern Ireland has also entered a new six-week lockdown, and the first week measures are the toughest yet, with a form of curfew in operation from 8pm, shops closed from that time and all indoor and outdoor gatherings prohibited until 6am.

Figures in Downing Street are due to meet with officials at the Department for Education on Monday to discuss whether schools should be kept open in the event that harder measures are needed, it is understood.

Mr Gove said the Government hopes the staggered reopening of schools in England will go ahead in January as planned.