Tanaiste Leo Varadkar is expecting restrictions to be in place for a while yet with cases likely to jump significantly again today.
The Fine Gael leader said it will be another 10 days or so before it shows if lockdown restrictions are working.
Cabinet is set to meet today to discuss Brexit but will also be speaking about the current Covid-19 situation.
Mr Varadkar told Morning Ireland: "We know that Level Three max did bring the R rate under one and brought the cases down and Level Five last time did as well.
"One of the concerns we have is the new variant which is part of the mix now which might change things.
"But we won't know for sure really until the first week or the second week of January because when restrictions come in there is a good 10-14 days before they begin to be reflected.
"We will certainly discuss Covid(at today's Cabinet meeting).
"What the CMO said yesterday is absolutely correct, a very small number of people attended for tests around Christmas Day and St Stephen's and that has shown an artificially low number yesterday.
"We would expect to see, no matter what is done, to keep rising until the first week of January."
The Tanaiste said that NPHET did recommend the full Level Five raft of risk restrictions that would have seen non-essential shops close.
But Mr Varadkar doesn't expect that to happen at the moment.
He added: "One thing we know from the modelling that opening non-essential retail in early December and in the previous, didn't have a major effect on the numbers so that's something we have to keep in mind.
"They recommended the full Level Five.
"We have to bare in mind that any restrictions we put in place now, could be in place for some time."
The plan also remains to open schools in January, and while restrictions are to be reviewed on January 12, Varadkar doesn't expect them to be lifted by then.
The Tanaiste said: "The Government has said we will review the current restrictions on January 12 and we will.
"I don't(see them being lifted).
"We can now foresee the point where we will have vaccinated those most at risk. There is a case to say those restrictions stay in place until that is done."
