Britain will be in the grip of a flu epidemic by the end of the month if the virus continues to spread at the current rate, figures released on Thursday suggest.
The new data comes as the heads of Accident & Emergency (A&E) units warned that hospitals were being forced to take “intolerable” safety risks, with patients dying in corridors.
Health service data shows flu rates are continuing to rise, with one in five hospital cases suffering from the most deadly strain, dubbled “Aussie flu” after it fuelled the country’s worst flu season for more than two decades.
The statistics show flu rates have doubled in the past fortnight, raising the spectre of an epidemic in the UK within a month if trends continue.
It comes as the consultants leading 68 NHS A&E departments wrote to the Prime Minister, warning of “appalling” safety risks because hospitals have too few staff and beds to cope with current demand.
The letter to Theresa May calls for a “significant increase” in funding for social care services, warning that the level of safety compromise in some hospitals has become “intolerable”.
The letter from the most senior doctors at A&E units across the country said the health service was "chronically underfunded" and ill-prepared for winter.
They said more than 50 patients at a time had been left waiting for beds in casualty units, with 120 patients a day being managed in corridors and "some dying prematurely".
Official figures published on Thursday show the worst A&E performance for 14 years, with some hospitals treating less than four in ten patients within four hours.
Meanwhile, norovirus cases have risen by almost a third in one week, while flu cases have continued to rise, fuelling 22,000 visits to GPs last week.
Monthly figures from NHS England show that in December just 77.3 per cent of patients treated at major units, known as type 1 A&Es, were seen within four hours - against a target of 95 per cent.
This is the lowest figure since records began being published in 2004.
The worst performance was at Blackpool Teaching Hospitals Foundation Trust, with just 40 per cent of patients seen within four hours last month, the figures show.
In total, 944 beds were closed because of winter vomiting and norovirus, compared with 731 the week before - a rise of 29 per cent.
The latest flu figures show almost 2,000 patients have received hospital treatment for confirmed flu so far this season.
More than one fifth are infected with the deadly strain A(H3N2) - dubbed “Aussie flu”.
The total death toll is now 85 after 27 deaths last week. The figures for England show rates of GP consultations about flu have risen from 18.9 per 100,000 people to 37.3 per 100,000 people in a fortnight.
If the trends continue, the country is on course to reach epidemic levels - of more than 109 cases per 100,000 people within a month. Such rates have not been seen in England since the winter of 2010.
Experts said flu had now “taken off” but said the virus was unpredictable. An epidemic has already been declared across the channel.
Prof Dame Sally Davies, England’s chief medical officer, pleaded with doctors and nurses to have the jab for the sake of their patients, with less than one third of healthcare staff vaccinated in some hospitals.
“Healthcare workers owe a duty to protect their patients – go and get vaccinated,” she said.
Officials also urged all members of the public who are eligible for jabs to come forward.
Victims of the flu outbreak include an 18-year old girl and a World War II spitfire pilot.
Bethany Walker, from Applecross, died after falling ill at home - initially from flu symptoms which later developed into pneumonia. Ms Walker was airlifted to Raigmore Hospital in Inverness but died last Friday.
Her mother Heather Teale said she was “truly devastated” by the loss of her daughter.
“I am broken, the bottom has fallen out of my world,” she wrote in a Facebook post.
“You were the best daughter I could have ever wished for and I will always be the proudest mum in the world.”
Owen Hardy, 95, from Chichester, died on January 4 after contracting flu, his daughter said.
During his time serving for the RAF in the war, the wing commander’s heroics saw him awarded the top medal for valour – the Legion d’Honneur.