Boris Johnson has said it is "absolutely crazy" that people are being put into intensive care because they are refusing the Covid vaccine.
The prime minister told a news conference on Tuesday afternoon that there were ample slots for people to get vaccinated but some people were still not being jabbed.
His chief medical officer Chris Whitty added that he was "saddened" by the numbers of unvaccinated people in intensive care, adding that "the great majority of them are not anti-vaxxers".
It comes after the prime minister said he was minded to stick to the government's so-called Plan B approach and not bring in further restrictions to fight the Omicron wave.
Mr Johnson told reporters: "How absolutely crazy it is, absolutely crazy, that there are two million slots this week for people to get vaccinated and yet the majority of people in ICU for Covid are not vaccinated - 61 per cent.
Recommended Johnson dismisses calls to scrap VAT from household energy bills Whitty saddened by unvaccinated in intensive care targeted by ‘misinformation’ Boris Johnson sticks with Plan B in bid to ‘ride out’ Omicron without lockdown
"It is sad but it is also a huge opportunity for us to correct it."
Unvaccinated people are disproportionately likely to become severely ill from Covid and require hospital treatment or even die.
Professor Sir Chris Whitty has said there is "misinformation" on the internet "a lot of it deliberately placed" about the potential side effects of the jabs.
"In so far as I am frustrated it is simply people deliberately trying to scare away fellow citizens from something that is potentially going to be life-saving for them," he added.
Meanwhile Patrick Vallance, the government's chief scientific officer, said it would be "untenable" for everyone to be given booster shots "every three or six months".
He added: "That is not the long-term view of where this goes to. There may be some people who will require an additional dose, but longer term I would think that as this becomes a disease which is endemic... it will be something like an annual vaccine like flu or of that order."
UK news in pictures Show all 50
1/50UK news in pictures
UK news in pictures 4 January 2022 Freshly-fallen snow covers houses in Corbridge, near Hexham in Northumberland
PA
UK news in pictures 3 January 2022 Dean Morrison, 13, receives his Covid-19 vaccine from student nurse Anthony McLaughlin during a vaccination clinic at the Glasgow Central Mosque
PA
UK news in pictures 2 January 2022 Konastantinos Tsimikas of Liverpool with Chelsea’s Mason Mount during the Premier League match at Stamfrod Bridge
Liverpool FC/Getty
UK news in pictures 1 January 2022 New Year’s Eve Lasers, drones and fireworks illuminate the sky in front of the Royal Naval College in Greenwich shortly after midnight in London
EPA
UK news in pictures 31 December 2021 Competitors in fancy dress run across the Pennine tops near Haworth, West Yorkshire, in the annual Auld Lang Syne Fell race which attracts hundreds of runners every year
PA
UK news in pictures 30 December 2021 Sunrise at Bamburgh Castle in Northumberland
PA
UK news in pictures 29 December 2021 The Very Revd Dr Robert Willis, Dean of Canterbury Cathedral, looks at Becket, a six month old red-billed chough as he visits Wildwood Wildlife Park in Kent on the anniversary of the murder of Thomas Becket
PA
UK news in pictures 28 December 2021 Troops of the Household Cavalry are seen reflected in a puddle during the changing of the Queen’s Life Guard, on Horse Guards Parade, in central London
PA
UK news in pictures 27 December 2021 A pedestrian walks past a winter sale sign outside a John Lewis store on Oxford street in London
Getty
UK news in pictures 26 December 2021 Riders take their bikes through the snow near Castleside, County Durham
PA
UK news in pictures 25 December 2021 Patrick Corkery wears a santa hat and beard as waves crash over him at Forty Foot near Dublin during a Christmas Day dip
PA
UK news in pictures 24 December 2021 People stand inside Kings Cross Station on Christmas Eve in London
Reuters
UK news in pictures 23 December 2021 Christmas shoppers fill the car park at Fosse Shopping Park in Leicester
PA
UK news in pictures 22 December 2021 The sun rises behind the stones as people gather for the winter solstice at Stonehenge.
Getty
UK news in pictures 21 December 2021 People take part in a winter solstice swim at Portobello Beach in Edinburgh to mark the solstice and to witness the dawn after the longest night of the year
PA
UK news in pictures 20 December 2021 An auction employee displays poultry to buyers and sellers attending the Christmas Poultry Sale at York Auction Centre in Murton
PA
UK news in pictures 19 December 2021 Joao Moutinho of Wolverhampton Wanderers looks on during the Premier League match between Wolverhampton Wanderers and Chelsea at Molineux
Getty Images
UK news in pictures 18 December 2021 Freight lorries queuing at the port of Dover in Kent
PA
UK news in pictures 17 December 2021 Newly elected Liberal Democrat MP Helen Morgan, bursts 'Boris' bubble' held by colleague Tim Farron, as she celebrates following her victory in the North Shropshire by-election
PA
UK news in pictures 16 December 2021 Brussels sprouts are harvested by workers as they prepare for the busy Christmas period near Boston in Lincolnshire
PA
UK news in pictures 15 December 2021 Lewis Hamilton is made a Knight Bachelor by the Prince of Wales at Windsor Castle
PA
UK news in pictures 14 December 2021 The Royal Liver Buildings surrounded by early morning fog in Liverpool
PA
UK news in pictures 13 December 2021 People queue outside a walk-in Covid-19 vaccination centre at St Thomas's Hospital in Westminster
Getty Images
UK news in pictures 12 December 2021 People take part in the Big Leeds Santa Dash in Roundhay Park, Leeds
PA
UK news in pictures 11 December 2021 People arrive at a Covid-19 vaccination centre at Elland Road in Leeds,
PA
UK news in pictures 10 December 2021 Stella Moris speaks to the media after the US Government won its High Court bid to overturn a judge’s decision not to extradite WikiLeaks founder Julian Assange
PA
UK news in pictures 9 December 2021 Camels are lead around Salisbury Cathedral during a rehearsal for the Christmas Eve Service
PA
UK news in pictures 8 December 2021 Margaret Keenan and Nurse May Parsons, a year after Margaret was the first person in the UK to receive the Pfizer vaccine
PA
UK news in pictures 7 December 2021 Snowfall in Leadhills, South Lanarkshire as Storm Barra hits the UK with disruptive winds, heavy rain and snow
PA
UK news in pictures 6 December 2021 A person tries to avoid sea spray on New Brighton promenade in Wallasey as the UK readies for the arrival of Storm Barra
Getty
UK news in pictures 5 December 2021 People release balloons during a tribute to six-year-old Arthur Labinjo-Hughes outside Emma Tustin's former address in Solihull, West Midlands, where he was murdered by his stepmother
PA
UK news in pictures 4 December 2021 People walk through a Christmas market in Trafalgar Square
Reuters
UK news in pictures 3 December 2021 A pedestrian carries a dog as they dodge shoppers on Oxford Street in central London
AFP/Getty
UK news in pictures 2 December 2021 Duchess of Cambridge inspects a Faberge egg at the Victoria and Albert Museum
Getty
UK news in pictures 1 December 2021 Meerkats at London Zoo with an advent calendar
PA
UK news in pictures 30 November 2021 Workers put the finishing touches to the Trafalgar Square Christmas Tree ahead of the lighting ceremony later in the week
PA
UK news in pictures 29 November 2021 Home Secretary Priti Patel is greeted by a police dog at a special memorial service for Met Police Sergeant Matiu Ratana
Getty
UK news in pictures 28 November 2021 Riyad Mahrez of Manchester City battles for possession with Aaron Cresswell of West Ham United during a match at the Etihad during snow
Manchester City/Getty
UK news in pictures 27 November 2021 Residents clear branches from a fallen tree in Birkenhead, north west England as “Storm Arwen” triggered a rare “red weather” warning
AFP via Getty Images
UK news in pictures 3 December 2021 An aerial picture shows a worker using a quad bike and trailer to transport freshly harvested trees at Pimms Christmas Tree farm in Matfield, southeast England
AFP via Getty
UK news in pictures 26 November 2021 A shopper browses Christmas trees for sale at Pines and Needles in Dulwich, London
Reuters
UK news in pictures 25 November 2021 A murmuration of hundreds of thousands of starlings fly over a field at dusk in Cumbria, close to the Scottish border
PA
UK news in pictures 3 December 2021 A pedestrian carries a dog as they dodge shoppers on Oxford Street in central London
AFP/Getty
UK news in pictures 24 November 2021 Migrants are helped ashore from a RNLI (Royal National Lifeboat Institution) lifeboat at a beach in Dungeness, on the south-east coast of England, on November 24, 2021, after being rescued while crossing the English Channel.
AFP via Getty Images
UK news in pictures 23 November 2021 The coffin of Sir David Amess is carried past politicians, including former Prime Ministers Sir John Major, David Cameron and Theresa May, Speaker of the House of Commons Sir Lindsay Hoyle, Home Secretary Priti Patel and Prime Minister Boris Johnson during the requiem mass for the MP at Westminster Cathedral, central London
PA
UK news in pictures 22 November 2021 The scene in Dragon Rise, Norton Fitzwarren, Somerset where police have launched a murder probe after two people were found dead
Tom Wren/SWNS
UK news in pictures 21 November 2021 London-based midwife Sarah Muggleton, 27, takes part in a 'March with Midwives' in central London to highlight the crisis in maternity services
PA
UK news in pictures 20 November 2021 Police officers monitor as climate change activists sit down and block traffic during a protest action in solidarity with activists from the Insulate Britain group who received prison terms for blocking roads, on Lambeth Bridge in central London
AFP via Getty Images
UK news in pictures 19 November 2021 A giant installation of Prime Minister Boris Johnson made from recycled clothing goes on display at Manchester Central, as part of Manchester Art Fair, in a 'wake-up call for the Prime Minister to tackle textile waste'
PA
UK news in pictures 18 November 2021 The scene at a recycling centre in Stert, near Devizes in Wiltshire after a large blaze was brought under control. The fire broke out on Wednesday night the fire service has said and local residents were advised to keep windows and doors shut due to large amounts of smoke
PA
Sir Patrick also said: "The good news is that as you get vaccinated more the immune system broadens its response so that it covers more variants."
Recommended UK’s new Brexit negotiator said leaving EU would spell economic disaster Boris Johnson announces 100,000 critical workers will be tested for Covid every day England to stick with Plan B Covid restrictions, Boris Johnson announces
Over 90 per cent of people over 12 years old in the UK have had their first Covid vaccine dose as of the New Year, with more than 51.7 million Covid vaccines delivered up and down the country.
The government says there has been an almost 50 per cent surge in people coming forward for their first Covid vaccine as the booster programme continues.