The National Public Health Emergency Team has expressed "exceptional concern" about the impact of Covid-19 and the Omicron variant in its latest advice to Government tonight.
The recommendations include significant reductions in hospitality hours with a suggested 5pm closing time from next Monday.
NPHET is advocating that sporting, theatre and cultural gatherings should not take place after 5pm and capacity should be cut to 50%, or 5,000 people for outdoor events.
Close contacts of a confirmed case, who have not received a booster vaccine, will be advised to restrict their movements.
However, the current restrictions around allowing people from three households to gather in the home of a fourth are not set to be tightened.
It's understood the NPHET letter was not specific on weddings but it said all large gatherings are potentially super spreader events.
Schools are still on track to remain open until the Christmas holidays, according to the advice.
Ireland is also expected to stay aligned to EU policy on international travel.
All these latest recommendations will be considered by Government tomorrow.
Earlier. the Minister for Health told the Dáil that as of today, 27% of new Covid-19 cases are Omicron.
The number of Covid cases has levelled off, and the national effort against the Delta variant has worked, Stephen Donnelly said, during statements on the pandemic.
He has "very strong advice that the booster, critically, provides a dramatic and an essential additional level of protection against Omicron".
But while "the vaccines do provide significant protection against severe illness from Omicron", they provide "significantly less protection against becoming symptomatic," the minister said.
Ireland is third in the EU and eighth in the world in terms of booster uptake.
"Nearly all of the 1,300 GP clinics" nationwide have agreed to get involved in the programme, Mr Donnelly added.
Seven hundred pharmacies are involved, up from 550, and it is hoped to get that up to 1,000 in the coming weeks, the minister said.
The number of patients with Covid-19 in hospitals today stands at 443 - down 27 since yesterday. It is the lowest number since mid-October. Of these, 108 people are being treated in ICU, up three on the same time yesterday.
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The possibility of tightening restrictions on hospitality, before the NPHET letter was sent to Government, led the Restaurants Association of Ireland to warn that such a move would have a "devastating economic impact on businesses already flattened financially".
Taoiseach Micheál Martin said everyone recognised that Christmas is an important part of the year when families get together, but the Government would be nimble and agile to deal with the Omicron threat.
Speaking in Brussels, Mr Martin said today's EU Council Summit will focus strongly on Omicron with calls for stronger co-ordination around Europe to tackle the new variant.
Leaders will discuss the #Omicron variant and how EU countries can improve coordination on #Covid19 at today's summit in Brussels, Taoiseach @MichealMartinTD says, amid 'significant concern' over the capacity of the variant to spread rapidly. | https://t.co/2t9wFp7e98 pic.twitter.com/KLV4Au6kjU— RTÉ News (@rtenews) December 16, 2021
"There's a general desire, even from my meetings this morning among new prime ministers for stronger and greater co-ordination around the administration of the booster vaccine, the scientific evidence underpinning in terms of the interval period and also the digital certificate, in terms of co-ordinating all of that over the next while," he said.
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Mr Martin also said indications were that there would be better scientific data in respect of Omicron in the coming weeks, in terms of not just its transmissibility, but its severity, which he said was "a key question."
Looking ahead to the NPHET meeting, he said issues had been teased through and added: "They will make the recommendations. Suffice to say they are very concerned ... at how fast this variant spreads."
Mr Martin's said Ireland's strength would be the high participation in the first and second doses of the vaccine.
"You add the booster and you're in a strong position to deal with this," he said.
Health professionals have 'growing dread' over Omicron impact
A consultant in Infectious Diseases at Beaumont Hospital has said there is a "growing dread" among health professionals about what may lie ahead as the Omicron variant spreads.
Dr Eoghan De Barra said while it remains to be seen how the variant will affect the number of patients in hospital, there will "almost certainly be a big impact on staffing numbers" and the ability to deliver care.
Meanwhile, a consultant in infectious diseases at St James's Hospital has called for mask wearing to be extended to the under-nines and a greater concentration on ventilation in schools after Christmas.
Dr Clíona Ní Cheallaigh said that closing schools early could be damaging for children, particularly those for whom school is a life line.
Additional reporting: Fergal Bowers, Paul Cunningham