Omicron XE: 'Hybrid virus' most transmissible Covid variant to date

In the UK, over 1,200 cases of the XE variant have been recorded. File picture

A new variant of the Omicron strain of Covid-19, believed to be about 10% to 20% more transmissible, is likely to be circulating in Ireland, a leading immunologist has said.

Cases of Omicron XE, a recombinant or combination of the previous Omicron BA.1 and BA.2 variants, have already been detected in the North and Britain.

To date, the Department of Health has confirmed just a single case here.

Professor of experimental immunology at Trinity College Dublin, Kingston Mills, said such recombinations are common among viruses such as influenzas.

"We had Omicron, and that was a new variant that emerged in December, and then there was a subvariant of that called BA.2, which is now the dominant variant in Ireland and a lot of other European countries," he said. 

He said that when different variants are circulating, and a person gets infected by them, the viruses can often recombine, giving rise to a "type of hybrid virus, which is a mixture of the genome of one and the other".

"So what you have with Omicron XE is a bit of the BA.1 virus and a bit of the BA.2.

Professor Kingston Mills of Trinity College Dublin. File Picture

"It has the spike protein from the BA.2 version, and some of the internal proteins are from BA.1."

In the UK, over 1,200 cases of the XE variant have been recorded.

Prof Mills said that, though the XE variant may not be any more severe than BA.2 or Omicron, it still poses a threat to older and vulnerable people, particularly those who are unvaccinated.

He said countries such as India, where over 6m new cases have been recorded so far this month, have seen several new variants emerge.

"I am not trying to be scaremongering but we need to be prepared if we do see a variant that completely evades immunity with the vaccines — that's the big concern," he told RTÉ Radio's Morning Ireland.

"The current vaccines prevent severe disease with Omicron, BA.2, and probably this new XE as well, but if we got another variant that completely evaded it, we'd be back to square one."