Thousands of patients are having surgeries and clinic appointments cancelled as hospitals are in danger of running out of critical-care beds for people who are seriously ill with Covid-19.
Hospitals are at risk of struggling with between 1,500 and 2,500 Covid-19 patients by mid-January with potentially between 200 and 400 in intensive care.
There are just 286 fully staffed intensive-care beds.
A spokeswoman for the HSE said critical-care surge plans are in place if demand exceeds this, "but with the knowledge that this affects the standards of care for all critical care patients and that this has an outcome impact, particularly beyond 350 beds".
"As such, it is their advice that, where possible, demand should be controlled so as not to exceed capacity," she said.
The number of Covid-19 patients admitted to hospital rose again yesterday to 776, with 70 in intensive care.
There was a jump of 92 hospitalisations in 24 hours.
University Hospital Galway is having to cancel all but very urgent time-critical surgeries for two weeks.
It will also be postponing outpatient clinics and some will be conducted virtually.
There are fears the impact of the cancellations will lead to more unnecessary delayed diagnoses and serious illness among patients with non-Covid conditions.
Although urgent care is being prioritised, there are concerns that some patients may deteriorate.
HSE chief Paul Reid said yesterday he expected to come to an agreement with private hospitals to take on some public hospital care later this week.
He described the impact on hospital intensive care as one of "high and extreme risk".
Around 3,000 staff are out due to Covid-19, either as a result of infection or because they are a close contact.