The Health Service Executive has confirmed that outpatient appointments have been cancelled at St Columcille's Hospital in Loughlinstown, Dublin due to an outbreak of Covid-19.
The HSE said that patients have been notified and virtual clinics are continuing.
Earlier, the hospital said its Medical Assessment Unit would close for two days from this evening because of the coronavirus outbreak.
In a statement, it said that patients who require care are being redirected to St Vincent's Hospital at Elm Park or to St Michael's Hospital in Dún Laoghaire.
The Medical Assessment Unit provides treatment to those who have been referred to the hospital by a GP with symptoms including chest infection, pneumonia, fever, deep vein thrombosis and urinary tract infection.
The statement said that 31 patients in the hospital have tested positive for Covid-19 and that while progress has been made to stabilise the situation, "ongoing work will be required to provide for additional capacity".
Fifty-eight nursing staff are not available because they have the disease or are a close contact of a case. Some staff are expected to return to work early next week.
A total of 454 people are employed at St Columcille's Hospital.
The Medical Assessment Unit is separate to the Injuries Unit which remains open to treat people with conditions including head injuries, broken bones, sprains and strains.
Clinical director says virus outbreak 'a big problem'
The clinical director for St Columcille's Hospital said the Covid-19 outbreak there is "a big problem" and shows there is no room for complacency with the virus.
Dr Donal O'Shea said: "You can see the writing is on the wall" when an asymptomatic patient tests positive as the level of precautions taken would not be same as if they had the disease.
There are four wards in the hospital, Dr O'Shea said, and one of these is exclusively for Covid-19.
There is a close contact ward, another ward is closed and the remaining ward "is just about continuing to function," he added.
Dr O'Shea said the hospital is hopeful it can restore services after the 48-hour closure of the Medical Assessment Unit as the number of patients who are positive has decreased slightly and the people who are testing positive are close contacts.
He said that St Columcille's Hospital is 250 years old and the infrastructure makes infection prevention and control really challenging but the hospital has managed well.
The outbreak is disappointing but underlines there can be no complacency, he added.