Less than half of NHS staff have had their flu vaccines this year and there are warnings that “time is running out” as the virus threatens to engulf hospitals before Christmas.

A free flu jab is offered to all frontline health workers including doctors and nurses, but NHS data shows that only 43.2 per cent have taken it up.

Low uptake among children and NHS staff is fuelling the worst outbreak on record for this time of year, which health officials say has left them in the “worst-case scenario”.

A combination of “vaccine fatigue” and antivax sentiment has led to lower uptake since the Covid pandemic, when three quarters of staff got their vaccines.

Some four million children aged between 2 and 17 remain unvaccinated. Outbreaks in this age group have driven a surge in cases.

On average 2,660 patients were in hospital with flu every day last week, the highest on record for this time of year. Wes Streeting, the health secretary, has said a “tidal wave of flu is tearing through our hospitals”.

Hospital admission rates for flu in England overall are highest among people over 75 and children under five.

Conall Watson, of the UK Health Security Agency, said: “There is still plenty of flu vaccine available to protect those who need it. What’s running out is time to be protected ahead of Christmas. If you are eligible this is the last chance to get protected as we head into Christmas, so make an appointment with the NHS today.

Should you get an NHS flu jab?

“If your child has missed out on their vaccination with the school immunisation team, you should still be able to get vaccinated through a community clinic over the next few weeks. Contact your NHS school immunisation team to find out arrangements in your area. The school should be able to provide their details if you can’t find them directly. Vaccination can make all the difference in preventing severe illness and hospitalisation for those eligible.”

So far this year, 17.4 million people have received the NHS flu jab, about half of the total eligible.

Flu jabs are offered by the NHS to all children, adults aged 65 or over, pregnant women and under-65s at clinical risk due to underlying health conditions such as asthma. For adults, the flu vaccine is administered as an injection. Children are typically offered a nasal spray in school.

Streeting said the NHS was facing its biggest challenge since the pandemic and that hospital admissions could triple in the coming weeks. He said he was “genuinely fearful” for the health service if a five-day strike planned by the British Medical Association went ahead next week. Asked on LBC if the collapse of the NHS was at “one minute to midnight”, Streeting replied: “Effectively, yeah.”

He added: “The thing I’m genuinely fearful of is that, even if I throw more money at this situation now, at this time to get through the next week on strikes, there’s only a finite number of doctors and staff. There’s only a finite number of care home beds and community-based care.

“So if you’ve got strikes and you’ve got flu and you’ve got all of these trolleys on corridors, and you’ve got demand going up rather than down, I just don’t think there is a lever I can pull, I don’t think there’s an amount of money I can throw, that means I can guarantee patient safety over the next week.

“That’s a pretty terrifying position, not just for me to be in, but for the doctors and NHS staff who are confronting that challenge to be in, because they are the ones that are going to be bearing it on the on the front line. I’ll be there with them if these strikes are going ahead. I’m not going to bury my head in the sand or look the other way. I’ll go and see it first-hand.”

It comes as polling commissioned by the government and conducted by YouGov has found that 58 per cent of those surveyed did not support the upcoming resident doctors’ strikes.

The government has put a fresh offer to resident doctors which focuses on job opportunities and training places. The BMA is putting the offer to its members, but it is expected they will reject it as it makes no concessions on pay.

Commenting on the polling, Streeting said: “Patients are pleading with doctors not to abandon them this Christmas.

“With flu sweeping across the nation and the health service under enormous pressure, these cynical Christmas strikes are the very last thing the NHS needs.

“People answer the call of medicine to help people, and this is the health service’s hour of need.”

He urged the BMA to accept the deal, adding that it was in the “best interests” for the doctors and patients.

Sir Keir Starmer said that it was “beyond belief” that doctors were striking as the NHS prepared for the “coming storm”.

“I am a Labour prime minister, who believes in workers’ right to strike,” he wrote in the Guardian. “But let’s be clear when it comes to the strikes planned by resident doctors next week. They should not happen. They are reckless.”

The BMA responded on Saturday morning by accusing Streeting of “scaremongering”. Jack Fletcher, the chairman of the BMA’s resident doctors committee, said the health secretary was “laying the blame for the failings of the NHS to cope with an outbreak of flu at the feet of resident doctors”.

Fletcher said: “It is horrible for anyone to be suffering with flu — we are not diminishing the impact of that — but Mr Streeting should not be scaremongering the public into thinking that the NHS will not be able to look after them and their loved ones.”