The Chief Medical Officer has warned that the average five-day Covid-19 case count is rising, describing it as "a worrying development which has persisted for the last few days".
There has been one more death associated with Covid-19, the Department of Health has confirmed, bringing the overall death toll in Ireland to 1,979.
There were 378 more cases of the coronavirus reported, bringing the total number of cases reported so far to 67,903.
As of 2pm on Sunday, 249 Covid-19 patients are hospitalised, of which 31 are in ICU.
There were five additional hospitalisations in the previous 24 hours.
Of the cases notified today, 186 are men and 190 are women.
There were 124 cases in Dublin, 34 in Donegal, 23 in Louth, 19 in Cork, 19 in Limerick and the remaining 159 cases are spread across 20 other counties.
The department said 63% of today's cases are in people under 45 years of age, with the median age being 38 years old.
Dr Tony Holohan said the average daily five-day case count "is rising and is now over 400 per day".
"This is a worrying development which has persisted for the last few days," he said.
"We are seeing a number of things which concern us. There are examples of small numbers of people congregating for social purposes and simply ignoring the important public health messages. They are putting our collective progress at risk.
"We are also seeing number of outbreaks across the country. These include outbreaks in association with funerals.
"We understand that this is a difficult time for families but it is really important that we do everything we can to avoid the circumstances which promote transmission of the virus.
"There have also been outbreaks associated with workplace settings. As we head into a new working week, we need stay at home other than for essential reasons and for personal exercise within 5km. Anyone who can work from home, should work from home."
It comes after latest figures showed the number of confirmed cases of Covid-19 in hospitals had reduced to 249. This is five fewer than yesterday evening.
In Northern Ireland, nine further deaths associated with Covid-19 have been recorded, seven of which occurred in the previous 24 hours, taking the official death toll in Northern Ireland to 855.
There were 472 new cases of the virus recorded, from tests on 2,709 individuals.
The total number of cases recorded in Northern Ireland now stands at 46,831.