NHS chiefs have issued an extraordinary plea for families to help them discharge loved ones even if they are Covid-19 positive as the health service faces a “perfect storm” fuelled by heavy demand, severe staff shortages and soaring Covid cases.

Hospitals and ambulance services across England are under “enormous strain”, health leaders have warned, after NHS trusts covering millions of patients declared critical incidents or issued stark warnings to residents.

Dr Layla McCay, director of policy at the NHS Confederation, which represents the whole healthcare system, said the situation had become so serious that “all parts” of the health service were now becoming “weighed down”. This will have a “direct knock-on effect” on the ability of staff to tackle the care backlog, she added, as well as the current provision of urgent and emergency care.

On Wednesday evening, the crisis became so acute in Hampshire and the Isle of Wight that its chief medical officer urged relatives of patients well enough to be discharged to collect them immediately – even if they were still testing positive for coronavirus.

Dr Derek Sandeman, of the Hampshire and Isle of Wight Integrated Care System, revealed that almost every hospital in the two counties was full, and said the number of people with Covid-19 being cared for in hospitals across the area was 650 – more than 2.5 times higher than in early January. He added that 2,800 staff working for local NHS organisations were off sick, half of which absences were due to Covid-19.

“With staff sickness rates well above average, rising cases of Covid-19 and very high numbers of people needing treatment, we face a perfect storm – but there are some very specific ways in which people can help the frontline NHS and care teams,” said Sandeman.

“If you have a loved one who is in hospital, please help staff to help get them home quickly when they are well enough – even if they are still testing positive for Covid. That is enormously important to help us make beds available for those in greatest need.”

Earlier on Wednesday, a major ambulance trust, South Central Ambulance Service (SCAS), which covers 7 million people across Berkshire, Buckinghamshire, Hampshire, Oxfordshire, Sussex and Surrey, declared a critical incident after “extreme pressures” forced it to prioritise patients with life-threatening illnesses.

At the same time, six hospitals across Yorkshire issued a joint warning for people to stay away from emergency departments except for in “genuine, life-threatening situations” after a surge in numbers left some patients waiting for up to 12 hours.

“With nearly 20,000 people in hospital with coronavirus in England, these latest critical incidents highlight how once again the pressure on our health service is mounting,” McCay said. “Ambulances, A&E departments and frontline providers of care across all parts of the NHS are weighed down by heavy demand.”

Saffron Cordery, deputy chief executive of NHS Providers, said NHS trusts “right across England” were under “enormous strain” caused by rising numbers of people with Covid-19 in hospital, a very high number of beds being occupied, staff absences and severe workforce shortages. “Trust leaders and everybody in the NHS are keenly aware of the impact of delays and addressing them is an absolute priority,” she added.

SCAS declared a critical incident on Wednesday after a huge volume of callouts the previous day and asked people to call 999 only in life-threatening or serious emergencies.

Meanwhile, hospital trusts across West Yorkshire and Harrogate in North Yorkshire – an area covering more than 2.5 million people – said the current pressures had left them with no choice but to prioritise patients presenting with acute illness or injuries.

West Yorkshire Association of Acute Trusts (WYAAT) said its most recent emergency department figures showed a 14.2% increase in attendances compared with the same week last year.

Dr Andrew Lockey, emergency medicine consultant with Calderdale and Huddersfield NHS Foundation Trust, said: “Our hospitals are extremely busy, and people are having to wait a long time to be seen.”

An NHS England spokesperson said: “NHS staff remain under significant pressure on many fronts as they deal with high numbers of ambulance callouts and increasing numbers of people in hospital with Covid-19, while the latest weekly figures also show a spike in the number of staff off sick due to the virus.

“Despite this, NHS teams across the country are working hard to deliver as much routine care as possible as well as rolling out the spring booster programme, so if you have a health concern, please come forward for the care you need – and if invited, get your vaccine at the earliest opportunity.”