The first cases of a new Covid-19 variant of concern have been confirmed in Ireland.
The two cases of BA.4 were discovered here earlier this month.
They were identified from whole genome sequencing performed on a proportion of confirmed virus cases in the week of 7 May.
BA.4 is a subfamily of the highly transmissible Omicron, which is currently the dominant Covid strain in Ireland.
The European Center for Disease Prevention and Control reclassified BA.4 and another subdivision of Omicron, BA.5, from variants of interest to variants of concern on 12 May.
They were first discovered in South Africa in January and February this year, where they have become dominant.
‘No indication of any change in severity’
The ECDC said that the growth benefits of the two strains “are probably due to their ability to evade immune protection induced by previous infection and / or vaccination, especially if this has diminished over time”.
It also said: “there is currently no indication of any change in severity for BA.4 or BA.5 compared to previous Omicron genera.”
The total share of the two tribes in Europe is currently low.
However, the ECDC said: “the presence of these variants may cause a significant overall increase in Covid-19 cases in the EU / EEA in the coming weeks and months”, and based on the high growth rates reported, it expects that they will become dominant subgenera.
The two BA.4 cases in Ireland were confirmed in the weekly letter from Chief Medical Officer to Health Minister Stephen Donnelly on 13 May.
No case of BA.5 was detected here on that date.
Dr. Tony Holohan said: “The overall epidemiological situation in Ireland currently offers a largely positive outlook, although we will have to continue to monitor developments with new variants over the coming weeks.”