Visitors have been banned from Waterford Regional Hospital in an attempt to stop the spread of the highly contagious norovirus bug.
The ban follows an outbreak of the gastro-intestinal virus - currently seven patients are ill with telltale symptoms such as vomiting and or diarrhoea.
The HSE says the ban will only be lifted in exceptional circumstances.
People who fall sick with norovirus symptoms are urged to stay away from the hospital and to drink plenty of water. They should call their GP before visiting the surgery, the HSE said.
"Patient care is our priority," said Patricia Sullivan, general manager of the hospital. "We would appeal to the public who may have experienced vomiting and or diarrhoea, to avoid visiting the hospital or nursing home until they are symptom-free for 72 hours (three days), and ensure good hand washing practices."