Experts are monitoring a new Omicron sub-variant of Covid, dubbed BA.2.
More than 400 cases of the strain have been reported in the UK so far, with infections multiplying in some parts of Europe and India.
And health officials in Denmark say BA.2 now makes up around half of all confirmed Omicron cases in the country, and there are suggestions it may outcompete the original BA.1.
However, Danish authorities say that initial analysis shows no difference in hospitalisation for BA.1 compared to BA.2.
As of January 19, Ireland has confirmed four cases of the BA.2 variant, according to Chief Medical Officer Dr Tony Holohan's latest letter to Health Minister Stephen Donnelly.
The World Health Organisation says the strain is currently not a “variant of concern”, meaning there is no evidence to suggest the subvariant could worsen transmission, illness severity or effectiveness of vaccines.
However chief Tedros Adhanom Ghebreyesus said on Monday that conditions “are ideal” for more variants to emerge.
Health experts, including the WHO, are studying the new subvariant.
A WHO report from last week reads: "While the BA.1 lineage has previously been the most dominant, recent trends from India, South Africa, the United Kingdom, and Denmark suggest that BA.2 is increasing in proportion.
"Drivers of transmission and other properties of BA.2 are under investigation but remain unclear to date."
The UK Health Security Agency has designated BA.2 as a “variant under investigation”.
UKHSA’s Dr Meera Chand UKHSA, said: “It is the nature of viruses to evolve and mutate, so it’s to be expected that we will continue to see new variants emerge as the pandemic goes on.
"So far there is insufficient evidence to determine whether BA.2 causes more severe illness than Omicron BA.1, but data is limited and UKHSA continues to investigate.”
On Monday, Ireland confirmed 9,218 new cases of Covid-19. It comes as the country emerges from the first weekend where almost all restrictions were lifted.
Health Minister Stephen Donnelly has warned Ireland is not out of the woods yet on Covid and could be hit with “more variants of concern” in the coming months.
Mr Donnelly told RTE’s This Week programme on Sunday: “The infectious disease experts community that I’m speaking to, and the virologists, say, look, we could have more variants of concern.
“We could have mutations of Omicron, that may be more severe, so obviously we have to keep an eye on that.
“But certainly this wave of Omicron, we look to be well through that, the numbers are right down.”
