An intensive care consultant at University Hospital Limerick says hundreds of staff are out due to COVID-19 reasons.
There are 141 patients with the virus in UHL, making it the second worst-hit hospital in the country.
Additionally, there are only two critical care beds available in the facility.
Cork University Hospital has the highest number of patients on site with the virus at 152, with only one critical care bed available.
In total, there are 1,846 people with coronavirus in hospital nationwide.
It comes as 50 additional deaths related to COVID-19 and 3,498 more cases were confirmed in Ireland yesterday.
Intensive Care Physician at UHL, Dr Catherine Motherway, said staff absences are "significantly impacting" services across the hospital group.
Speaking on Newstalk Breakfast with Susan Keogh, she said healthcare workers are "run off their feet".
"Across all grades, we have people out, either who have contracted COVID in the community, a close contact in the community, a close contact at work, or contracted it at work," she said.
"I think the figure was between 400 and 500 yesterday across all sites.
"Nursing is particularly impacted, as is medicine."
Dr Motherway explained that sometimes it is "absolutely necessary" for some healthcare staff to return to work after ten days.
She said: "There has always been a policy that if you are vital to a service and you are a close contact and you're asymptomatic that at various stages it will be safe potentially for you to return to work, both for you and for the patients."
This would involve the individual being swabbed at day five, swabbed at day ten and then maybe being asked, "if it's absolutely necessary", to return to work at day ten.
This worker would also be asked to monitor their symptoms and take their temperature twice a day before returning.
Dr Motherway expects the hospital system to still be under pressure in the coming weeks, but said there are some good indicators that transmission on the community is decreasing.
"We have a large burden of disease but the numbers in the community are beginning to turn down and there are some hopeful signs," she said.
"But we will continue to be under pressure, I would imagine, for a number of weeks."
On the gradual reopening of the country, she said ICU numbers and capacity should not be used as metrics in deciding when the current lockdown can end.
It comes as Tánaiste Leo Varadkar told The Hard Shoulder this week that ICU numbers need to be below 50 before reopening.
"I think we should open up when we have a critical mass of people vaccinated and we definitely have every vulnerable person in the country vaccinated," Dr Motherway stated.
"Obviously, ICU figures are really important and one of the reasons that we had such severe lockdowns is that I think everybody became acutely aware at the beginning of this that our ICU capacity is way below where it should be.
"That said, nobody should use ICU or ICU numbers in terms of looking at opening up, let's say you double up the ICU numbers then you can let everybody loose and get COVID.
"Nobody wants anyone to get COVID, so I think the most important thing the Tánaiste said was that community numbers were low and we had a critical mass of people vaccinated."