There's a "clear change" in the way Covid-19 is spreading, with younger people now accounting for the vast majority of cases in this country.
All of the 23 newly-confirmed cases last night were people under 45 years of age, with 15 under the age of 25.
The National Public Health Emergency Team says people need to take immediate care and caution.
Acting Chief Medical Officer, Dr. Ronan Glynn, is appealing to younger people to be sensible if gathering this weekend.
Also there's an "immediate need" for care and caution, as the Covid-19 reproductive rate now stands "at or above one".
That's according to the National Public Health Emergency Team (NPHET),
The 'R number' shows the average amount of people that an infected person will pass the infection on to.
Chair of the COVID Modelling Advisory Group, Professor Philip Nolan said it's concerning news.
He said: "It looks like each case currently is leading to another case. We'd prefer it wasn't, and [are] working hard to ensure it doesn't.
"I think the note of caution is that we have clusters and outbreaks, and each and every one of us need to do everything we can to ensure a cluster or outbreak doesn't lead to unnecessary further transmission of disease.