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.
Meanwhile, there could be a five-fold increase in the number of Covid patients in hospital, due to the Omicron variant.
NPHET says the figure could top 2,000 next month - compared to 419 at the moment.
The head of the Saolta group of hospitals in the west, Tony Canavan, says he's very concerned.