The HSE has issued a warning over a potentially deadly new wave of swine flu, also known as H1N1.
The flu strain has killed at least two people so far this winter and has hospitalised many others.
HSE's Assistant National Director for Public Health, Dr Kevin Kelleher said that it could turn into a serious public health issue.
Dr Kelleher said, "I know it's difficult not to let your child go to school, or not yourself go to work, but it is important if you've got these symptoms."
He advised that it’s not too late to get the flu vaccine and vulnerable people in particular are being urged to do so.
Symptoms include the usual flu aches and pains, cough and loss of appetite, but it can also lead to more serious chest problems such as pneumonia.
Anyone suffering from these symptoms should stay home from work or school and stay in bed.
This particular strain can be a serious concern for people aged under 65, especially those with pre-existing conditions as well as pregnant women.
You can find more information on what to do if you're suffering from the flu on the HSE's website here.