A further 3,394 cases of COVID-19 have been confirmed in the Republic - the highest daily number ever recorded.
This brings the total number of cases here to 96,926.
A further four deaths were also confirmed, bringing the total number of deaths here to 2,252.
Of the 3,394 cases, 389 occurred in Cork, 355 in Dublin, 339 in Donegal, 258 in Louth and 233 in Mayo.
As of 2pm on Saturday, 607 patients with COVID-19 were hospitalised, 56 of whom were in ICU. There had been 71 additional hospitalisations in the past 24 hours.
According to the Department of Health's chief medical officer, Dr Tony Holohan, the incidence of COVID-19 is now as high, if not higher, than it was in March.
"Every individual needs to act as if they are infectious. Hospitalisations are rising to levels close to what we saw in the springtime. Everyone needs to stay at home, other than for essential work or care.
"It is really important that vulnerable and older people do not leave their homes unless absolutely essential. This includes asking neighbours or family to carry out errands such as grocery shopping, limiting all contacts to only those people you live with or have to visit for essential care reasons," Dr Holohan said.
He called on people to "rediscover the spirit of solidarity and community" that was evident in March and April.
"People particularly vulnerable to COVID-19 include older persons and people with pre-existing medical conditions, including cardiovascular disease, obesity, diabetes, chronic respiratory disease and cancer,' he added.
The national 14-day incidence rate in the 14 days up to midnight on January 1 was 381.6, however 10 counties were above this, with Monaghan the worst affected, at 783.6.
Wickow had the lowest 14-day incidence up to January 1, at 162.2.
Meanwhile, the positivity rate in COVID tests has risen from 5.5% on December 19 to 21.9% on January 1.
Ireland is now is level 5 of the Government's COVID plan. For more information on this, click here.
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