The chief medical officer says Covid cases are rising sharply among young adults, due to the Omicron variant.
The positivity rate among 16 to 34 year olds has jumped to 25 per cent - one of the highest rates since the pandemic began.
The five-day moving average of Covid cases has also risen above 5,000, after increasing by 16 per cent in the past week.
Dr Tony Holohan says the spike in infections among young adults is down to the new variant.