The country is to return to Level 5 restrictions, with a number of exemptions, from Christmas Eve until at least 12 January.
Taoiseach Micheál Martin said the move was in response to the extraordinary increase in Covid-19 cases, with a 10% daily growth rate that is "simply not sustainable".
The Government said that "certain transitional arrangements" to the Level 5 restrictions will apply during the Christmas period.
Here are some of the main changes that were announced today:
Restaurants and gastro-pubs will close at 3pm on Christmas Eve. Hair and beauty salons will also close on Christmas Eve.
Up until St Stephen's Day, visits from up to two other households will be permitted. Household visits will be reduced to one other household from 27 December.
In both cases, a 'support bubble' is counted as one household.
No new inter-county travel will be allowed after St Stephen's Day, which means that people must stay in their own county from 27 December.
From 1 January, no household mixing will be allowed, except for essential family reasons, such as providing care to children, elderly or vulnerable people.
Non-essential retail can remain open, but shops will be asked to postpone January sales.
A double rate of Covid Restrictions Support Scheme (CRSS) will be paid for two weeks to businesses that are forced to close on 26 December.
Hotels may provide food and bar services to guests only after 3pm on Christmas Eve. Hotels may only open to guests for essential purposes after 26 December.
Christmas Day religious services can take place and then services will move online from 26 December. However, places of worship will remain open for private prayer.
The number of guests allowed at weddings will remain at 25 until New Year's Day, then from 3 January the number of guests will be reduced to six.
Schools will return as normal in January after the Christmas break, while childcare services and early learning will also continue as normal.
Gyms, leisure centres and swimming pools can remain open for individual training only.
Non-contact training in pods of up to 15 can take place outdoors and golf and tennis clubs will stay open.
No matches/events should take place, except for professional and elite sports, and horse racing and greyhound racing behind closed doors.
Here are some of the other main restrictions that apply under the Level 5 plan:
No organised indoor or outdoor gatherings should take place.
Up to ten mourners only are permitted at funerals.
People should continue to work from home, unless it is essential to travel for work.
Higher, further and adult education should remain primarily online.
Public transport capacity will be restricted at 25%.
Outdoor playgrounds, play areas and parks will remain open.
Museums, galleries, libraries and other cultural attractions will close.
Nightclubs, discos and casinos will remain closed.
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