Schools, colleges and cultural institutions across the country are set to close over the COVID-19 outbreak.
The Taoiseach made the announcement in Washington this morning, with the measures in place from tonight until March 29th.
He said there will be "many more cases" in Ireland and will continue to spread across the world - and that measures are now needed to try and halt the spread of the virus here.
The measures come into effect from 6pm today, with schools, colleges, childcare facilities and cultural institutions (such as museums, galleries and tourism sites) to close from tomorrow.
Schools and colleges to close from tomorrow pic.twitter.com/pLzonugx3y
— Seán Defoe (@SeanDefoe) March 12, 2020
He said people should continue to work where they can, but should work from home wherever possible.
Mr Varadkar said: "In order to reduce unnecessary face-to-face interaction in the workplace, break times and working times should be staggered and meetings done remotely or by phone."
People are being advised that indoor mass gatherings of over 100 people and outdoor gatherings of over 500 people should be cancelled.
Public transport will continue to operate, and shops, restaurants and cafés will be allowed to remain open.
However, businesses are being advised to put in place measures to implement advice on public distancing.
He said the economy 'will suffer', but measures are in place to ensure the supply chain is not implemented.
Mr Varadkar said: "It's going to involve big changes in the way we live our lives, and I know that I'm asking people to make enormous sacrifices.
"But we're doing it for each other - together we can slow the virus in its tracks and push it back."
Donald Trump overnight announced he was banning flights from most of Europe from entering the US for 30 days due to the coronavirus.
Ireland and the UK were not included on the list of impacted countries, with the travel restrictions instead in place for the 26 Schengen countries.
It will also apply to people who have been in the Schengen countries 14 days before attempting travel to the US.
Health officials confirmed nine more cases in the Republic yesterday, bringing the total here to 43.
Including Northern Ireland - where 18 cases have been confirmed - the total number of confirmed cases on the island is currently at 61.
The Mater Hospital in Dublin earlier said it was limiting all activity to "essential services only" over the COVID-19 outbreak.
From today, most outpatient appointments and elective surgeries are being deferred until further notice.