Donegal has been highlighted as one of the worst affected areas for flu cases this winter.
Eight people have died from flu-related illnesses this season across Ireland, including five in the past week.
The HSE says Donegal and Dublin are worst-hit by the virus.
Three hundred people have been admitted to hospital in the past week with flu, while over 620 cases have been reported so far.
Letterkenny University Hospital remains closed to visitors as a result of the outbreak, while emergency departments nationwide are under increased pressure.
The HSE is warning that the death toll could rise, as the virus commonly increases in January. The majority of deaths already reported have occurred in adults of 65 years of age.
