The Irish health system is under “inconceivable strain”, one of the country’s top health officials has warned.

HSE chief executive Paul Reid said the service is facing the “highest level of impact and risk we’ve had to manage since Covid landed here”.

He told a briefing on Thursday: “The situation in our hospitals and healthcare systems overall is very serious,” as they struggle to deliver both regular care and respond to the pressures of the fourth wave of the virus.

Mr Reid warned that services will face “unyielding and unrelenting strain over the next while”.

In response to warnings from health officials, the Government earlier this week announced fresh measures in a bid to reverse the surging number of cases.

Pubs, nightclubs and restaurants must now close at midnight, and people are being urged to work from home from Friday if they can.

There will also be a more widespread use of antigen testing.

Currently, 643 people are in hospital with Covid-19 – a 20% increase over the last week.

The number of people in intensive care is now 118.

A further 4,650 cases of Covid-19 were confirmed in Ireland on Thursday evening.

Mr Reid warned that unvaccinated people continue to make up a disproportionate share of intensive care patients.

Of the 476 patients in ICU between June 27 and November 13, 61% were either unvaccinated or only partially vaccinated, Mr Reid told reporters.

“I state it because our clinical teams are asking us to state it very clearly,” he said.

Pressures caused by treating Covid-19 patients will lead to the cancelling and curtailment of elective care in some of the largest hospitals, Mr Reid warned.

Hospitals are currently building up surge capacity in intensive care beds, Mr Reid said.

He also said the HSE will again be relying on private hospitals to boost capacity.

“We’re appealing again to the public not to attend emergency departments unless there is an emergency need,” he added.

The Government has faced questions about what opposition politicians have labelled a sluggish rollout of the booster programme.

Mr Reid said the capacity of vaccination centres is being expanded, but he warned the HSE’s resources are currently significantly stretched.

Damien McCallion, HSE national director of the Covid vaccination programme, confirmed the organisation has reached an agreement with a private testing company at Dublin Airport.

He also said new staff are being recruited for community test centres, which are processing around 150,000 swabs each week.

Mr Reid defended the need to rely on a private company to boost testing.

“We’re doing both,” he told reporters.

“It’s a combination of scaling up completely within the HSE resources. So our lab capacity, our swabbing capacity, our swabbing centres all across the country.”

“We have a resourcing demand that we have never seen anything like it before.”

“We do have to go where we can get further activity right now.”

Mr Reid also suggested health workers may be made exempt from new rules requiring household close contacts to restrict their movement for five days pending completion of antigen testing.

He told reporters at the briefing on Thursday: “We’re working through right now in terms of how a derogation would apply to healthcare workers.”

He suggested health staff would be able to go to work, while also taking antigen tests and being monitored for any changes in temperature.

Such an arrangement was used by the HSE at earlier stages of the pandemic to ensure the health system did not become understaffed.

Members of the National Public Health Emergency Team have said they will continue to monitor the situation regarding rising cases, but ministers have warned further restrictions cannot be ruled out.

On Wednesday, Chief Medical Officer Dr Tony Holohan said there could be 200,000 Covid-19 infections in December – but this could be prevented.

Colm Henry, chief clinical officer at the HSE, said the grim situation facing the health system could be reversed.

He said the country’s 14-day incidence rate currently stands at 1,211, although he added that early indications suggest the booster programme is having a positive effect on the rate of cases among the older population.

“We are not all helpless bystanders. We all can and should play our part,” he said.