Three cases of the Brazilian variant of Covid-19 have been detected in Ireland for the first time, the Department of Health said.
All are directly associated with recent travel from the South American country, the authorities said.
They are being followed up by public health teams and enhanced measures have been put in place.
Ireland’s deputy chief medical officer Dr Ronan Glynn said: “Anyone who has recently travelled from Brazil, or any of the other 19 countries recently designated by the Minister for Health as ‘Category 2’, is required by law to quarantine at home for 14 days.”
The Brazil variant could be much more contagious or easy to catch than the original version of coronavirus.
It has undergone changes to its spike protein – the part of the virus which attaches to human cells.
It first emerged in July.
Dr Glynn added: “This P1 variant has previously been identified in a small number of European countries, including France, Germany, Italy, the Netherlands and Spain.
“While there is currently no microbiological or epidemiological evidence of any change in transmissibility of P1, this is plausible.
“Further studies are required to determine whether this variant is likely to have an impact on vaccine effectiveness or infection severity.”
Around 90% of Covid-19 cases in Ireland are associated with the UK variant.
Numbers of new infections and pressure on hospitals has eased and the death toll has begun to abate following weeks of tough curbs.
The emergence of new coronavirus variants introduces significant uncertainty in predicting when society can return to normal, public health experts have said.
The Republic recently passed the grim milestone of 4,000 dead from the disease during the latest wave of mortality.
Taoiseach Micheal Martin has warned tough restrictions to slow the spread of disease could remain in place into April.
Schools and childcare will reopen on a phased basis next month after health experts gave the green light to Government to begin easing weeks of strict lockdown.
Next week ministers are expected to update their Living with Covid plan.
Ireland has also ramped up its vaccination programme.
Another 80,000 doses of Covid-19 vaccines were administered this week, with a further 100,000 doses expected next week.
An additional 28 people have died with Covid-19, the Department of Health said on Friday.
Another 763 infections were confirmed.
A total of 151 people were in hospital intensive care units on Friday morning.
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