There has been an increase in the number of people with Covid-19 in hospital, however case numbers in intensive care units remain stable.

Latest figures show there were 717 people with the virus in hospitals around the country this morning, up 61 on yesterday.

Of these, 87 people are in ICUs with Covid-19, an increase of two.

The Department of Health has reported a further 17,071 confirmed cases of Covid-19.

Minister for Health Stephen Donnelly has said while case numbers are high, hospitalisations are lower compared to this time last year.

In a post on Twitter, he said Ireland has the second highest uptake of booster vaccines in the EU and described the vaccine rollout as "superb".

The minister said studies suggest that people are eight times more likely to end up in hospital with Covid-19 if they are unvaccinated.

He also said that while Ireland's critical care/ICU capacity has increased, "much more is needed".

At the start of 2020, he said, there were 255 adult critical beds and now there are 296, adding that more ICU beds will open this year and he has brought a proposal to Cabinet to increase overall critical care capacity to 446 beds.

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The Covid-19 vaccine booster programme has opened to all remaining cohorts aged 16 and older.

Following changes announced on Friday evening, the Health Service Executive invited people aged 16 to 29 who have already completed their primary course of Covid-19 vaccine to come forward for their booster dose.

They must book into a vaccination clinic for their age group and will be offered a single dose of the Pfizer/ BioNTech vaccine.

The accelerated roll-out is taking place amid a steep rise in confirmed Covid-19 cases.

In the week since Christmas Day, more then 120,000 people have tested positive, which is more than the total positive cases recorded in the whole of 2020.

Under new advice from the Government regarding PCR tests, those aged between four and 39 are asked to take regular antigen tests if they have symptoms of the virus.

If they receive a positive antigen test, they should then book a PCR test to confirm they have coronavirus.

If they have repeated 'not detected' antigen tests, they should still self-isolate for 48 hours after their symptoms have gone.

Meanwhile, the Health Service Executive has said it expects more hospitals will have to curtail non-essential work in the coming days, because of the high number of staff absences due to Covid-19.

A Consultant Microbiologist at Tallaght University Hospital has said clinical teams there have been "decimated" by Covid-19.

Dr Anna-Rose Prior said they are not seeing the same disease severity as this time last year, but added, "we are still under extreme pressure as the absolute numbers coming through the door are still quite high."

Speaking on RTÉ's Brendan O'Connor programme, she said the pandemic was having a "huge toll" on staffing levels at the hospital with people off work due to either having Covid-19 or being a close contact.

"Our clinical teams have been decimated - they are trying to provide care with minimal staff," she said.

Dr Prior also said the PCR test system has come under extreme pressure and now was a good time to use antigen tests, but no test is 100% perfect.

"If you are at home with symptomatic people, if you yourself are symptomatic, you cannot believe one negative antigen test.

"Hence there is the requirement to do several, I think the recommendation is to do three, one test is never enough," she said.

Dr Prior said anyone with symptoms of Covid-19, given that the prevalence is so high, should assume they have it and isolate at home.

"I think most people will do the right thing. There will always be people who take assurance from that one negative - that is always the concern - but I think the majority of people know the pitfalls of antigen testing."

Separately, the Rotunda Hospital in Dublin has said its Emergency Department is extremely busy and has asked people to attend only if absolutely necessary.