The number of vacant NHS hospital beds in England is lower than at any time since the start of the Covid-19 crisis, as the health service contends with a wave of infections unleashed by the Omicron variant while attempting to clear a massive backlog of outstanding treatment.

In the week ending April 12, an average of just 4,933 adult general or acute hospital beds were unoccupied across England, according to a Financial Times analysis. This is the lowest level recorded during the coronavirus pandemic, and represents 5.4 per cent of the total.

It shows the NHS has less spare bed capacity than at any time in the past two years and calls into question its ability to meet a commitment to increase non-urgent hospital treatment by 30 per cent above pre-pandemic levels over the next three years.

Nigel Edwards, chief executive of the Nuffield Trust, a health think-tank, said the FT research revealed “an unsustainable level of [bed] occupancy . . . No hospital system can run at that level of occupancy outside of very short periods of crisis.”

The squeeze on hospital beds would inevitably result in patients waiting longer in accident and emergency departments to be admitted, and perhaps being sent to wards without the specialist staff and equipment to meet their needs, he added.

Edwards said that in some instances “it will certainly mean that planned [operations] will have to be postponed or cancelled at short notice”.

The UK government announced in February plans to lift all remaining coronavirus restrictions in England, and the most recent NHS data suggest the latest wave of Covid hospitalisations involving the highly infectious Omicron offshoot BA.2 may have peaked.

But the NHS is under exceptional strain in relation to bed availability, which is recognised as a key measure of the resilience of a health system. Hospitals are considered to work most safely and effectively when more than 10 per cent of beds are available.

The FT research found that only 5.4 per cent of adult general or acute hospital beds were vacant in the week ending April 12, compared with 6.3 per cent at the height of the initial Omicron wave. During the 2020-21 winter, the figure was 9.2 per cent because far more beds were deliberately kept empty to create space for Covid patients.

NHS data released last Thursday showed a record 6.2mn people in England were waiting for non-urgent hospital treatment. These care backlogs have been exacerbated by the pandemic.

Chris Hopson, chief executive of NHS Providers, which represents healthcare organisations, said more than 15,000 patients were at present in hospital with, though not necessarily because of, Covid.

In addition, more than 20,000 patients medically fit to leave could not be discharged because the right care was not available at, or closer to, home, he added.

“That’s placing even more strain on bed capacity,” said Hopson. “And this at a time when the NHS is doing all it can to address care backlogs — so that’s another pressure.”

The issue of bed availability is about much more than infrastructure, he added. “You also need the staff to provide the care.” The NHS had 110,000 staff vacancies, a problem compounded by very high absences, many of them caused by Covid, he added.

Dr Rachel Kaminski, a respiratory consultant at Gloucestershire Hospitals NHS Foundation Trust, said the “vast majority” of patients had come in with ailments other than Covid and had only incidentally tested positive for the disease.

However, they still needed to be segregated which, in turn, was causing delays to operating schedules and prolonging discharges, placing more pressure on a limited bed base, she added.

A senior official at an NHS trust elsewhere in the south-west said local hospitals were being “absolutely battered” by the current Covid wave in addition to a “constellation” of other pressures, including clearing the treatment backlog, difficulty in discharging patients to social care, and an increase in people visiting emergency departments.

The official added that “the risk-benefit of infection control measures” had “completely changed with the latest wave”, and there was an expectation that social distancing and Covid testing rules in hospitals would be relaxed in the near future.

He also said that as a result of clinicians falling ill from the Omicron variant BA.2, the trust was facing “the biggest mismatch of staff to patients that we’ve had at any point during the pandemic”.

Dr Katherine Henderson, president of the Royal College of Emergency Medicine, a professional body, said staff shortages were particularly affecting emergency departments.

She said running an emergency department at the moment was “like flying a plane with half the crew and three passengers to every seat. No airline would take off under those circumstances but we have to.”

Henderson expressed concern the current strain on the NHS could be a “glimpse” of the “new normal”.

“Every single metric in emergency care is worse than ever before and it’s going to take a huge change around to get things better, even to get back to how bad we were in December 2019 — when I was quite firmly saying this is the worst it’s ever been,” she said.

She added that ambulance delays were “the thing that freaks us out most . . . [The NHS has] always been there for you in life and death situations — and now there is a real worry that we’re struggling to get ambulances out to people and . . . to get patients into emergency departments, simply because the system is so clogged up.”

The NHS said that, while hospitals planned ahead to increase winter bed numbers to help ensure patients could be quickly admitted, “having more than a tenth of beds taken up by Covid patients has had a knock on effect”.

Despite these pressures and high levels of bed occupancy “we have managed to admit near record levels of A&E patients and do hundreds of thousands more diagnostic tests than last winter”.

This had been achieved while reducing the number of patients waiting more than two years for treatment which fell for the first time in February, it added.