Authorities at Dublin's Beaumont hospital say visiting restrictions will remain in place throughout the Easter weekend.
Patients are asked to stay away from the unit, as hospital chiefs battle to contain an outbreak of flu, that has so far struck down 187 people at the hospital since February.
The warning also covers St Joseph’s Hospital in Raheny and the Raheny Community Nursing Unit. Only absolutely essential visits will be allowed.
Doctors say flu can be contagious a day or more before the symptoms start, and a person with flu can continue to spread the virus to others for up to a week after symptoms begin.