A new variant of Covid-19 - designated EG.5 and named Eris - has been detected in Ireland, according to the Health Service Executive.
The variant is a descendant of Omicron.
The World Health Organization has not designated EG.5 as a variant of concern or a variant of interest, but the lesser rating as a variant under monitoring (VUM).
The HSE said that Eris is more transmissible than previous circulating variants and has been associated with outbreaks, including in hospitals in Ireland and elsewhere.
It said there is currently no evidence of increased clinical severity of infection in Ireland with this strain.
Eris has become established in the UK and the US.
A rise in cases internationally is being driven by several factors, including greater indoor mixing, increased international travel and waning immunity.
Meanwhile, the HSE has recorded a further rise in Covid-19 cases in hospitals.
There are now 408 cases in hospital with the virus, up from 121 two weeks ago.
Of these, 12 people are in ICU with the virus, compared with 11 two weeks ago.
The HSE said that the overall number of patients in ICU with Covid-19 remains low.
A number of hospitals and healthcare institutions have reported outbreaks in recent weeks, including Galway University Hospital and St Luke's in Kilkenny.
Since the pandemic, there have been over 1.7 million PCR confirmed cases of Covid-19 in Ireland and 9,125 deaths recorded.