The Taoiseach has said he can't guarantee COVID-19 restrictions won't be reimposed over the winter if cases spiral out of control.
Micheál Martin was speaking on the day nightclubs can reopen after being closed for 18 months.
Restrictions are also easing for pubs, restaurants, weddings and religious services.
The vast majority of all remaining legal restrictions had been due to lift today, but due to the rising number of COVID-19 cases and hospitalisations, some measures will now remain in place through the winter.
The use of COVID-19 vaccine certs for access to indoor venues is set to continue until February.
Taoiseach Micheál Martin is currently in Brussels, with COVID-19 still a major item on the European Council agenda.
He said he can't rule out reimposing restrictions if there's another rise in cases.
He said: "The bottom line is that COVID-19 doesn't facilitate anyone guaranteeing anything.
"There could be mutations... anything can happen in relation to a global pandemic.
"The positive side is that we're learning all the time: the experts in science, through vaccines and therapeutics, are developing greater knowledge about the virus and giving us greater capacity to deal with it."
He says mitigation measures like vaccinations, a booster campaign and the retention of COVID passports will help this winter.
Mr Martin said he’s also receiving feedback that most nightclubs are happy to reopen tonight - despite the new guidelines being issued at the last minute.
He noted that the nightlife sector, artists and performers have had a "very, very tough time" over the past 18 months.
Nightclubs are welcoming back customers for the first time since March 2020, and are allowed open at 100% capacity.
Meanwhile, pubs and restaurants can now stay open beyond 11:30pm.
Customers can also queue to get a drink at the bar - but they must be socially distanced.