The Health Service Executive has warned that levels of influenza and respiratory illness have almost doubled across the country over the past two weeks.
It is urging those at risk who have not yet done so to get vaccinated.
The HSE says the rate is expected to increase further in the coming weeks.
Those at risk can get the flu vaccine from their local GP or pharmacist.
There have been several outbreaks of influenza-like illnesses in both residential care facilities and in acute hospital settings throughout the country, but particularly in the Dublin area.
The predominant flu strain is AH3 which is affecting mostly older people rather than younger age groups.
One person has died due to influenza this winter, according to the HSE Health Protection Surveillance Centre.
The latest figures show that in the week to 18 December there were 50 hospitalisations, bringing the seasonal total to 96.
Most cases have involved people 65 years of age and older.
Minister for Health Simon Harris has called on all those who have yet to get vaccinated to do so immediately.We need your consent to load this rte-player contentWe use rte-player to manage extra content that can set cookies on your device and collect data about your activity. Please review their details and accept them to load the content.Manage Preferences
