The flu season is expected to peak this week or next and will continue for up to six weeks thereafter.
The HSE said there has been a more than 10% increase in the number of patients attending hospital last week compared to the same week last year.
The Executive also said all possible surge beds, to cope with the extra demand are open.
Kevin Kelleher from the HSE said we still have not reached peak flu.
"I would suspect that we will peak this week, maybe just next week," he said.
"Then you will see the same decline over the next four to five weeks. It is important to note when I say 'peaks' it doesn't collapse," he added.