Pregnant women and high risk patients are being urged to get the flu vaccine.
It comes after the HSE has said up to 10 people have died as a direct result of the virus - a child is among the confirmed fatalities in the last week.
Peter Greally is Clinical Director of the Children's hospital group.
He has said common sense should prevail when you are visiting a patient in hospital; “Obviously, if people are visiting a hospital, standard hygiene rules apply.
“So where possible, sneeze into a tissue, careful discarding of tissue and materials like that, using hand hygiene throughout all hospitals.
“Common sense precautions will reduce the spread of many viruses.”