Shortages of the Pfizer vaccine have forced the NHS to slow the rollout of jabs despite ministers promising to use the delay to the ending of Covid restrictions to vaccinate as many people as possible.

Supplies of the Pfizer jab to virus hotspots in which Covid case rates are rising among younger groups have been cut, The Telegraph has learned.

Boris Johnson said on Monday that delaying the reopening would give the NHS crucial weeks in which to accelerate the vaccination programme.

Ministers have brought forward the target to offer all adults a first dose, and said over-40s should receive their second more quickly. 

But analysis reveals that the rate at which jabs are dispensed is slowing and is set to keep falling further.

Overall, just 1.2 million first doses were dispensed in the last week, compared with more than three million a week in earlier stages of the programme, with the UK now lagging behind Germany, Italy and France.

How many first doses have been given in your local area?

On Tuesday, the head of the NHS said the service was unable to go any faster amid limited supplies of Pfizer, the main vaccine offered to anyone under 40. 

Supplies are so short that staff at some mass vaccination centres have been told their shifts will be cancelled in the coming weeks, according to a leaked letter seen by The Telegraph.

Meanwhile in Salford, Greater Manchester, where the case rate is among the highest in the country, health bosses have been told to expect Pfizer supplies to drop from 3,500 doses this week to only 2,200 doses next week.

Hotspot areas warned that the July 19 unlocking could be derailed unless they received more supplies. 

In London, health officials requested 367,000 extra Pfizer and Moderna doses, with Sadiq Khan, the capital’s mayor, claiming the boost would allow people to "return to doing more of the things we love".

Ian Ward, the leader of Birmingham City Council, warned that the city would be "in exactly the same position" by July 19 unless the Pfizer shortage could be tackled.

"Unless the Government can deliver the Pfizer or Moderna vaccines in the right numbers, it’s hard to see how we could safely unlock on July 19 – and that goes for the whole country," he told The Telegraph.

If the rollout had kept going at the rates achieved in March, all first doses could have been administered by June 1, analysis by The Telegraph suggests, with all second jabs by the end of August or earlier if the gap between doses had been speeded up.

Instead, the rollout is working to administer all first doses by July 19 and may not be completed until Oct 11.   

Nahim Zahawi, the vaccines minister, has admitted that Pfizer supplies will be "tight" over the next few weeks.

"Pfizer have done a great job in being consistent on their delivery schedule," he said, adding that the company had done "remarkable things to increase their production, not just for us but for the whole world, for Europe and the US as well. But it is tight".

A Pfizer spokesman said: "In the UK, quarter one deliveries, January to March, were completed in line with our contractual agreement, and we remain on course to continue to deliver a steady supply of vaccines to the UK in accordance with the monthly schedule agreed in advance with the Vaccines Taskforce."

‘The rollout can go no faster than supplies allow’

It was the only rabbit the Prime Minister was able to brandish from a very tattered hat. 

Amid the bad news – the country will remain stuck in restrictions for another four weeks – the rollout of vaccinations would be accelerated, Mr Johnson said. 

Jabs are the biggest weapon in the virus war and, with this in mind, all over-40s will be offered second vaccines sooner, with the target for first doses brought forward. 

In fact, the changes to the rollout have merely prevented it from shuddering to a near-halt.

While Britain is on track to give second doses to all over-50s by next week – and has now given both jabs to 30 million adults – without changes to the schedule it would have fallen into a lull for two weeks before over-40s became eligible, according to analysis by The Telegraph.

How many people have been vaccinated?

Meanwhile, a closer look at the Prime Minister’s headline pledge reveals the scale of its ambition. According to the government data, speeding up second doses will only require vaccinations to run at half the current pace. 

While two million people got second jabs in the last week, just six million in their 40s and 50s are due second jabs in the next five weeks in order for the Government to hit its target. 

In truth, senior health sources said, the speeding up of second doses was not a major challenge because most were AstraZeneca, of which supplies are plentiful. 

But the programme of first doses is moving far more slowly in younger groups. Thanks to decisions by the Joint Committee on Vaccination and Immunisation (JCVI) to largely restrict AstraZeneca to older people, the rollout is now almost entirely dependent on Pfizer and is only managing to give around 1.2 million doses a week compared with three million a week in March. 

On Tuesday, Sir Simon Stevens, the NHS chief, told a conference of the NHS Confederation that the rollout can go no faster than supplies allow. The programme has opened to those aged 23 and over and is expected to open bookings to all over-18s later this week, but some have been forced to wait several weeks to secure a slot.

Last week, NHS England announced that a "drive to the finishing line" over the coming four weeks would see £20 million in extra funding handed to GPs and local vaccination centres to increase staffing.

But staff at mass vaccination centres have instead been warned to expect their shifts to be cancelled due to shortages of the Pfizer vaccine. In a letter seen by The Telegraph, NHS bosses at Derbyshire Community Health Services NHS Foundation Trust told staff and volunteers at the Derby Arena centre that they may not be required to come into work.

Staff at the Derby Arena vaccination centre, pictured in March, have been warned that 'Derbyshire will not be receiving large quantities of the Pfizer vaccine'

Credit: Oli Scarff/AFP

"As Derbyshire will not be receiving large quantities of the Pfizer vaccine, which we need for the younger cohorts, it means activity at the vaccination centre will be reduced for a few weeks," the letter said.

"This inevitably means some shifts will be cancelled, and I’m very sorry for the inconvenience this may cause. I’m hoping this at least gives you a chance to take a well earned break and recharge your batteries ready for when we have a better supply. We are being advised there will be more vaccine in July to carry on with our younger adults."

MPs are understood to have challenged the health minister Edward Argar over Pfizer supply shortages during an all-party Zoom call on Tuesday morning.

In Birmingham, GPs were said to have "no Pfizer in the fridge", with only enough supplies to vaccinate 10 per cent of the city’s 18 to 29-year-olds against the spreading Indian or delta variant.

Ian Ward, the leader of Birmingham City Council, said the Government may have to abandon plans to fully ease restrictions on July 19 unless the Pfizer shortage is addressed swiftly.

"In four weeks’ time we will be in the same position unless we have vaccinated enough of those people below the age of 30, given the pressures on hospitals," Mr Ward told the Telegraph.

"In Birmingham, we’ve got 37 per cent of people unvaccinated in some areas because of our younger population. Unless the Government can deliver the Pfizer or Moderna vaccines in the right numbers, it’s hard to see how we could safely unlock on July 19 – and that goes for the whole country.

"We have told Matt Hancock that we need whatever increased supply they can get their hands on. We could be doing 100,000 jabs a week if we had enough vaccine. The Government say they plan to ‘lean in’ to the problem, but I have no idea what that actually means."

Liam Byrne, the Hodge Hill MP, said GPs in his constituency had warned that "there is no Pfizer left in their fridges". 

"There is no certainty about when it is going to arrive, and they do not know how much they will get when it does come. We cannot unlock until we unblock this pipeline," he said.

Health leaders in Salford have been told to expect Pfizer supplies to drop next week, despite the area experiencing among the highest Covid case rates in the country, with 311.4 infections per 100,000 people.

"They’ve told us to expect 3,500 doses of Pfizer this week, and then only 2,200 doses next week," said Barbara Keeley, the Worsley and Eccles South MP.

"When the virus was peaking in Bolton, they were vaccinating 4,000 people every day. But we simply aren’t getting the supplies. The whole point of the month delay was meant to be to get more jabs in arms – and that won’t happen at this rate."

The challenge has been further complicated by family doctors increasingly giving up their vaccination responsibilities in order to restore normal service to patients.

"They feel they need to go back to concentrating on business as usual and then come back in the autumn when there will be a need to give booster shots," said Prof Martin Marshall, chairman of the Royal College of GPs.

A Department of Health and Social Care spokesman said: "There are no shortages of Pfizer/BioNTech vaccines and deliveries are coming in on time and as ordered.

"Our vaccination programme continues to make phenomenal progress, with more than 71 million vaccines administered so far –including 30 million second doses – and we are on track to offer a jab to all adults by July 19. We have been clear that everyone who is due a second dose should receive it on schedule."