Chief Medical Officer Dr Tony Holohan has said he 'couldn't rule out' coronavirus restrictions lasting until March.
He said there is currently no indication coronavirus infection rates are slowing down.
It comes as Ireland has again moved into a full level five lockdown, in a bid to tackle the latest spike in cases.
There is a ban on household visits, while non-essential retail will shut from close of business on Thursday.
Travel is also limited to five kilometres from your home, and a ban on travel between Ireland and Britain has been extended until January 6th.
Six people will be permitted to attend weddings, while 10 mourners may attend funerals.
Dr Holohan told Late Breakfast With Mark Cagney suggestions that the restrictions could last into March are a possibility.
"I can't rule that out, I couldn't rule that out - but at the moment, we have a four week opportunity."
"I know this wouldn't be possible - but if every single person could isolate themselves from every other person in the population for a period of 14 days, the whole infection would disappear".
"At the moment I'm not able to tell you that I see any sign that suggests that this is slowing down, unfortunately.
"With that very high level of infection it's going to take quite an amount of time - if I can say - to wash that level of infection out of the population.
"So we have it all to do in the four weeks until the end of January".
Virus 'is out of control'
And he said the measures have worked before, even though they are difficult.
"They're very hard to have to accept again, both economically and the restrictions on personal lives and freedoms and all of those things.
"But we do know that if we keep a very high level of compliance, that most of us have held all the way through this, we know already that this is a measure that can work".
"It's unfortunate that we have to take it, but we're in the situation now where we need a measure - because this virus is out of control in the population".
He said the number of contacts people have been reporting has been rising.
"We've seen a very significant increase in the number of contacts... on average per person.
"Some of those individual cases generating very large numbers of contacts - so clearly there are some people out there who are simply not in any way following the basic public health advice."
"When you have a case and you're able to identify 20 and 30 contacts, that's just a place we shouldn't be".
He said the average number of contacts per case has risen from around 2.5 in November, to an average of 6.3 in recent days.
He added that the measures introduced so far have prevented higher mortality rates.
"To the extent that we can compare how we've performed as a country with other European countries it did work.
"We kept mortality at a very low level in comparison to the European average."
"When we got to the end of November, the case numbers that we had were somewhere in the region of about 250 per day on a five day average - and that was a high level of infection in relative terms.
"When we began to ease restrictions then, we know we've seen a significant change in people's behaviour in terms of social contacts.
"When you put that together with the high case numbers, we've just seen a very rapid acceleration".
He said people can affect change to avoid Ireland falling into the same category as the rest of Europe.
"Even though we have a deteriorating situation... we still, at the moment, have one of the lowest incidences in Europe.
"What marks us out in Europe is that many other countries aren't deteriorating as quickly as we are."
But he said there is an opportunity that, if people follow the latest advice, "we can stop this infection from getting worse and getting to the levels that the rest of Europe is unfortunately seeing".
