Almost half of the new cases of Covid-19 reported on Saturday were in people under 35.
Six deaths were recorded, while there were 23 new cases.
10 of these or 43% were in people younger than 35.
The Chief Medical Officer has expressed concern that lifting of restrictions has led to people gathering in large groups.
Dr Tony Holohan said yesterday: “High levels of compliance to public health advice to date has enabled further reopening of economic and social life.
“However, of the 23 cases reported [on Saturday], 10 cases (43%) are in younger adults aged under 35 years. A further 8 cases (35%) are in those aged between 35-54.
“This is now a real concern and a worrying trend at a time when many people are reconnecting with friends and loved ones and may be gathering in larger groups.
“In recent days, for example, some cases have had large numbers of close contacts that have required testing and self-isolation for 14 days.
“Covid-19 is an infection that affects all ages and it is incumbent on all of us to take our individual responsibility seriously.
“I cannot emphasise enough how important it is to remain informed, keep a 2m distance from others and follow the public health advice on hand washing, cough and sneeze hygiene, and wearing face coverings.”
The CMO also advised people that this year, holidays should be about "staycations".
Writing on Twitter as the country prepares to move into Phase Three of reopening society, he said: "What worries me most now is travel from overseas and I fear many planning foreign trips.
"2020 is a year for a staycation. Stay in Ireland, spend locally and follow public health advice."