Healthcare staff who are working in "extraordinarily dangerous" situations are holding the State's "fragile" health system together, according to the Irish Nurses and Midwives Organisation (INMO).
Hospitals around the country have come under considerable strain over the past number of weeks due to a rise in hospitalisations linked to Covid-19 and influenza.
The union called on the HSE to do "everything necessary to protect the physical and mental wellbeing of nurses and midwives" as it confirmed there were 631 patients waiting on trolleys in hospitals on Thursday morning.
INMO general secretary Phil Ní Sheaghdha said hospitals "have never seen this level of activity at this time of year", adding that high levels of overcrowding are impacting care.
"Our fragile health service is being held together by an exhausted and burnt-out workforce."
Ms Ní Sheaghdha said there are currently 690 patients in hospital with Covid.
"We know that our public health system is not equipped to deal with providing emergency care, Covid care and elective care at the same time.
"The HSE must outline both locally and nationally what resources they are utilising from the private sector from now until the end of February. The health service, both public and private, must work as one."
She added that their members are "working in situations that are extraordinarily dangerous" and "there is now a real concern that nurses cannot provide safe care when conditions are so difficult, and rosters so stretched".
Thursday morning's trolley figures showed there were 514 patients waiting in Emergency Departments for a bed, while 117 patients were waiting elsewhere in the hospitals.
University Hospital Limerick was once again the most overcrowded hospital in the country, with 96 patients waiting, followed by University Hospital Cork (79) and Letterkenny University Hospital (50).
In the Eastern region, St Vincent's University Hospital had the highest number of people waiting for a bed (33), followed by the Mater Misericordiae University Hospital (19).
