The Taoiseach has told the Dáil that Covid-19 could have been circulating in Ireland late last year or in early January this year.
That is a number of weeks before the first case was officially confirmed in the country on 29 February.
Leo Varadkar said it cannot be assumed any longer that the virus came here from Italy in February.
The realisation that the virus was in France in December means that it could also have been here around that time, Mr Varadkar added.
He said this was because this country is closely connected to France, and France has many daily flights from China.
Testing and contact tracing will prove crucial to getting more answers and the HSE currently has the capacity to carry out 12,000 daily tests, he said.
Chief Medical Officer Dr Tony Holohan said that if Covid-19 was here before the first official case in February, then it would have been sporadic cases.
Speaking at the daily Department of Health briefing, Dr Holohan said he does not believe Ireland had infection here earlier than that at any significant level.
Asked about suggestions #Covid19 could have been in Ireland as early as last December, @CMOIreland says any cases before the first case was confirmed on 29 February would have been sporadic. Almost 400 tests were conducted before the first case was found. https://t.co/yro2bXPnFk pic.twitter.com/gHAFWxqHKr— RTÉ News (@rtenews) May 7, 2020
Meanwhile, the Taoiseach also told the Dáil that the €350 payment to people who have lost jobs due to the Covid-19 pandemic will be extended beyond mid-June.
He said there had been no decision regarding a new rate or a timeline and that a decision may have to be taken by a new government, otherwise it would be taken by the current administration.
Responding to questions from Sinn Féin leader Mary Lou McDonald, Mr Varadkar said that while the payment "could not continue forever", it would be extended beyond its current cut off date of mid-June.
Earlier, Ms McDonald said that the €350 was the bare minimum to "keep the show on the road" for families.
She said: "The reality is we will have an unemployment crisis well beyond the summer. Workers will need to be supported and protected. Workers do not need announcements that the €350 is about to be cut."