Health workers who were close contacts of coronavirus cases are being called back to work before they finish isolating for 14 days, it has emerged.
HSE chief operations officer Anne O'Connor confirmed that asymptomatic close contacts are being brought back to work "as a last resort".
The health system is under sustained pressure with the number of people in intensive care now higher than it was during the peak of the first wave.
Ms O'Connor said health officials made the decision because of the shortage of healthcare workers.
She said staff who were close contacts are being tested before they return to work and are being closely monitored.
Ms O'Connor told RTÉ Morning Ireland that the demand on the health system means the staff are needed to attend work.
"At the weekend we had to put a call out to staff to come into work at Letterkenny because we were under such pressure. I would see that happening in other sites," she added.
The head of the HSE, Paul Reid, tweeted: "Our hospitals are treating 1,750 people with Covid-19 and 158 critically ill in ICU. This is a level beyond comprehension.
"But to assure everyone, our healthcare teams are taking emergency actions to sustain this within a level of control. We appreciate your support."
The number of patients with coronavirus in intensive care jumped to 160 after the figures were updated following Mr Reid's tweet on Wednesday morning.
On Tuesday, the Government said all passengers arriving into Ireland from Saturday will have to provide a negative Covid-19 test taken before departure.
The check must be taken within 72 hours of arrival.
Arrivals from red and grey list countries (as defined by the EU traffic light system), and all other locations outside Europe, must continue to restrict their movements for 14 days.
However, this may be lifted on receipt of a negative/not detected result of a second PCR test taken no less than five days after arrival.
Arrivals from green and orange countries will not be required to restrict their movements on arrival but must adhere to local public health guidance.