The Department of Health has confirmed that 938 new cases of Covid-19 have been diagnosed in Ireland, 110 of which are in Cork, as of midnight last night.
Thirteen additional Covid-19 related deaths have also been notified to the Health Protection Surveillance Centre (HPSC) today.
Commenting, Dr Tony Holohan, Chief Medical Officer at the Department of Health expressed concerns about the latest data.
"Our level of concern continues to escalate.
"We must do all we can individually and collectively to change the course of this disease," he said.
"Revise your Christmas plans to ensure social contacts are limited and that hand hygiene, physical distance, ventilation and face covering measures are in place if you must have visitors to your home," he continued.
Of the confirmed new cases there are 300 in Dublin, 110 in Cork, 72 in Limerick, 68 in Donegal, 41 in Kildare and the remaining 347 cases are spread across 21 other counties.
416 are men and 517 are women, with 65% under 45 years of age.
As of 2pm today, 251 Covid-19 patients are hospitalised, of which 25 are in ICU.
There were 24 additional hospitalisations in the past 24 hours.
Earlier today, the National Health Emergency Team met and reviewed the current epidemiological situation and has made recommendations to the Government.
Dr Ronan Glynn, Deputy Chief Medical Officer, Department of Health said the epidemiological situation reviewed today is "the most serious it has been since last March".
"It is inevitable that people will get sick and die as a result of this escalation, but it is not too late for all of us to do all we can to minimise that impact and to protect as many people as possible," he continued.
Professor Philip Nolan, Chair of the NPHET Irish Epidemiological Modelling Advisory Group said the situation has "deteriorated further, even in the last two days".
"The reproduction number is higher than we have reported since March at 1.5 – 1.8.
"The day on day growth rate is estimated at 7 – 9%.
"These data emphasise the need for us to be exceptionally careful over Christmas and to adhere strictly to public health guidance," he said.
Dr Cillian De Gascun, Medical Virologist and Director of the National Virus Reference Laboratory said indications suggest the new strain of coronavirus is most likely in Ireland.
"However, given the timeline of the samples analysed, it would seem that the novel variant is not solely responsible for the recent increase in case numbers seen in Ireland," he said.
So far, there have been 2,184 Covid-19 related deaths in Ireland.