The HSE has begun accessing the surge capacity agreed with private hospitals as the system comes under increasing pressure, its chief executive has said.
Paul Reid said private hospitals have begun providing some non-Covid urgent care to public patients in recent days.
An agreement was reached between the HSE and private hospitals last week which gives the HSE access to additional capacity if needed.
"It would be surge up to 30% of bed utilisation which gives us in essence working with private hospitals over 600 beds to call on," Mr Reid told RTÉ Radio 1's This Week programme.
"We are, actually, calling on that right now. Already this week, private hospitals are taking some urgent non-Covid care and supporting us. So we have in essence triggered those processes already."
There were 37 vacant intensive care unit (ICU) beds as well as 11 paediatric beds on Saturday.
There were no critical care beds available at either Cork University Hospital or the Mercy University Hospital, according to a HSE report.
In total there are 286 ICU beds across the country, an increase on 255 at the start of the surge and the HSE is bringing in a further 16 ICU beds between this and next month.
Non-urgent care has been paused at public hospitals as the health system struggles to cope with Covid-19 cases but cancer care and cardio care continues.
Mr Reid said that the actions the health service has taken this week were geared towards helping the system cope in the coming days and weeks, but the situation is "concerning".
It comes as a record 1,421 coronavirus patients were being treated in hospitals across the country on Saturday morning.
The figure has more than quadrupled in the past two weeks, as 321 people were in hospital with the virus on December 27.
There were 136 additional admissions to hospitals in the past 24 hours.
Some 121 people are being treated for the virus in ICUs with 17 admissions in the last 24 hours.
There's now 1,421 people in hospital with #COVID19 (+136 today) & 120 in ICU. Our health system is under increasing strain.The best support we can all now give, is to avoid getting sick with Covid.This will help to get us out the other side of this. #StayHome #StaySafe @HSELive— Paul Reid (@paulreiddublin) January 10, 2021
Mr Reid predicted the number of people with Covid-19 in hospital in Ireland would reach more than 1,700 in the coming days, more than double the number it reached at its peak last year.
He said: "Early this week we will likely be at double what we had in the peak of last year which was 881 in the first phase of this. Our concern is the numbers. Our concern is the rising trend.
"I don't want people to feel powerless because actually what happens today: the actions people take today are what can really help us in the coming days and weeks."
He said the best support the public can give to health workers is to avoid getting sick with Covid-19.
He added: "Our health system is under increasing strain. The best support we can all now give, is to avoid getting sick with Covid.
"This will help to get us out the other side of this."
Dr Colm Henry, the chief clinical officer of the HSE, said the figures remained "worrying" and the fear is that they will continue to rise in the next fortnight.
He added the number of healthcare workers unable to work because of Covid-19 is a cause of concern.
"We are approaching 600 beds lost from our acute hospital system because of infection prevention control measures, because of staff who are sick due to Covid and because of staff who were close contacts," he told RTÉ Radio 1's Brendan O'Connor Show.
"And out there in nursing homes we have over 800 staff who similarly can't go to work because of Covid. So the impact is not just felt in terms of the numbers, it is on the huge secondary level of transmission, the destruction on healthcare and all the impact it has for patients, for staff."