Nightclubs are to shut for more than a month as part of new restrictions to curb the spread of COVID-19.
Under new measures, household visits will be limited to people from a maximum of three other households.
While the Digital COVID Certificate is being expanded to gyms.
Taoiseach Micheál Martin says the Government has accepted new NPHET recommendations.
- Nightclubs will close from December 7th until January 9th
- Bars and restaurants must revert to table service only, with one metre between tables
- There will be a maximum of six adults per table - with closing time remaining at midnight
- Bars, restaurants, and hotels must revert to the situation that was in place before October 22nd
- There will be a cap of 50% capacity at entertainment events, which must be fully seated
- 50% capacity also applies at cultural, community and sporting events
- Facemasks must be worn unless people are eating or drinking
- The Digital COVID Cert is to be expanded to gyms and leisure centres - as well as hotel bars and restaurants
- Visits to any one household must be limited to three other households at any one time (four in total)
There are no limits on numbers attending a wedding service and reception, while live music is permitted.
Opening his address to the nation on Friday, Mr Martin admitted: "My message this evening is a difficult one.
"It is difficult because even though Ireland has done very well as a country and you have done everything that has been asked of you, we have received some very stark advice from our Chief Medical Officer and our public health experts that requires the re-introduction of a number of restrictions.
"I understand and I share the disappointment and frustration that this will cause for many of you".
He also acknowledged that people did what they were asked and "stabilised the surge" and "as a country we pulled it back".
But he added: "Just as we were getting a handle on it, reports began to emerge of a new and potentially more dangerous variant of this virus.
"And last week, the World Health Organisation announced that Omicron was, indeed, a Variant of Concern.
"Just a few weeks ago South Africa was reporting approximately 300 cases per day.
"Yesterday it reported 11,500 new cases, on Wednesday it was 8,500, up on 4,500 the day before and 2,200 on Monday.
"We will do whatever we reasonably can to stop this new variant from circulating in the country, but we have already confirmed one case and all of our experience to date shows that while restrictions on travel are useful to delay the entry of new variants, it is impossible to stop them."
Mr Martin also praised the COVID booster programme.
"By tonight, close to 950,000 of our most vulnerable people will have received their third dose - a rate of distribution that puts us in the top four countries in Europe."
But he added: "The increased social mixing that normally comes with Christmas would put that under pressure in any case, but if Omicron takes hold and if it is more transmissible, the potential for a very serious crisis is obvious".
Sectors 'fearing for their livelihoods'
And the Taoiseach said industries affected by these changes will be supported, with many of them "fearing for their livelihoods."
"I want to reassure them that just as we have done since the beginning of the pandemic, the Government will stand by them and ensure that they have the financial supports necessary to weather this latest storm and to stay intact until we are out of it.
"We have demonstrated, through interventions and supports unprecedented in their scale and scope, that we will do whatever we need to do to safely steer our society and economy through this.
"And that has worked, in sectors all across the economy, with many hundreds of thousands of people back in work in industries that relied on Government support during the pandemic.
"We will continue this approach for those employers and workers affected by tonight's developments", he added.
Pandemic Unemployment Payment
The Government is to re-open the Pandemic Unemployment Payment (PUP) "for a limited period" to support people who lose employment arising from the new restrictions.
Social Protection Minister Heather Humphreys says: "I know many workers in the hospitality sector will be worried tonight
"The Pandemic Unemployment Payment will be open for applications for workers impacted by these latest restrictions.
"My department is finalising arrangements and full details will be announced, and the scheme will be ready for new applicants, by Tuesday."
She adds that further details on how individuals can apply for PUP will be announced "in the coming days".
While a Commercial Rates Waiver for businesses in the hospitality and live entertainment sector has been confirmed for the first quarter of 2022.
The Government says this will be put in place at a cost of approximately €62.3m.
See the full list of restrictions here