The number of people diagnosed with flu has soared since the start of the year.
The HSE is renewing its appeal for people in at risk groups to get vaccinated against the flu.
The organisation has said the majority of people who end up in hospital with serious complications from the illness have not received the vaccination.
Dr Darina O'Flanagan has said there is no reason to fear getting the flu jab: “It can’t give you the flu, the vaccine that we use in this country is a killed vaccine.
“So there is no possibility of you getting the flu from it, now it can cause a sore arm, but it definitely doesn’t give you the flu.”