It's likely the BA4 and BA5 variants will become the dominant strain of Covid in the coming weeks or months.
The variants, which were first identified earlier in the year in South Africa, have spread across Europe - with two cases confirmed here.
The BA5 variant now accounts for more than a third of cases in Portugal.
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Professor of Experimental Immunology at Trinity College Dublin, Kingston Mills, doesn't expect it to cause more severe disease:
