Minister for Health Jennifer Carroll MacNeill has appealed to “everybody who can” to get the flu vaccine, while confirming adults between 18 and 59 and not in at-risk groups will not get the jab for free.

Speaking on RTÉ Radio on Sunday, she said the strain of flu circulating was “very severe”, and particularly virulent among children.

“This virus is circulating most in children up the age of 15 ... [Children’s Health Ireland] normally don’t have any children on trolleys but at the moment they do and that’s as a consequence of the virus,” said the Minister.

The vaccine is free to children aged 0 to 17 years, anyone 60 or older, pregnant women, anyone with underlying conditions and to health workers.

Uptake among children stood at 21 per cent, she said – higher than last year’s 17 per cent, but still so low that some batches of the nasal spray vaccine for children had expired.

“The nasal vaccination has a 14-week expiry date ... So some of that has expired, but we have more of it. It’s not out everywhere. There are pharmacies that have it. We have additional supplies of it that don’t expire until January or February [and] there will be more available in coming weeks.”

Where the nasal vaccine was unavailable children could be vaccinated by injection.

Figures showed three quarters of people who are hospitalised with flu had not had the vaccination, she continued.

“I am asking everybody who can to go and get a vaccination. It takes about 10 days to kick in really, but this flu season will peak over Christmas. There will still be a sting in the tail into January.”

[ The Irish Times view on the flu wave: an early and unwelcome visitorOpens in new window ]

Asked her response to a Labour Party call for the vaccine to be free to everyone (it costs €30 to €35 for adults outside the identified vulnerable groups), the Minister said: “We have to take every year the best approach ... maximising resources that we have for the most vulnerable.

“If we [make it free for everyone] there are other things we can’t do. So that is the balance that we take.”

The uptake of just 29 per cent among healthcare workers remained a “concern”. The target for this cohort is 75 per cent.

“What we can do is make it available. It is free for healthcare workers. There are clinics where healthcare workers can get it on-site. We are asking people to get it for their own health, to prevent themselves getting sick [and to reduce transmission].”

Outlining measures to reduce pressure on hospitals, she said GPs were being funded to extend opening hours specifically for respiratory conditions while hospitals were implementing weekend discharges to keep patients moving from EDs and into wards.

“We are seeing extraordinary work to keep the patient flow going. [There are currently] 180 people on trolleys across 29 hospitals which is a really very, very good situation for any time of the year but particularly December, particularly during flu season.

“This time last year that would have been 600 people so it is very, very different and that is because of the changed way people are working and the huge commitment that they are bringing to their work every day as well.”