Professor Luke O'Neill has warned the latest Covid variant to arrive in Ireland needs to be monitored "very closely".
One case of Omicron XE, a new 'hybrid' strain of the BA.1 and BA.2 variants, has been reported in Ireland to date.
In Northern Ireland, a "small number" of cases of the new variant have also been discovered.
Trinity College Professor Luke O'Neill says that although the new strain shouldn't be a huge cause for concern, one aspect of the variant means it should be observed closely.
"We know it's recombinant...which means bits of Omicron have recombined with bits of BA.2, which is a sibling of Omicron, and bits of BA.1," he told RTE's Today with Claire Byrne programme.
"It's got three extra mutations that make it different from Omicron.
"The main thing is though it's mainly like BA.2 and that means it isn't causing a huge amount of concern because our immune system is holding up against BA.2 and Omicron XE seems to be very similar.
"But of course it's new and these three mutations that are brand new mean we need to watch it very closely."
The immunology expert said that the latest variant is around 10% more transmissible than Omicron, a strain which itself was four times more transmissible than Alpha and Delta.
This means Omicron XE is "already a good bit away from the original one in terms of transmissibility", he added.
"What is happening is that the virus is changing in to a much more transmissible form," Prof O'Neill outlined.
"The good news is, though, that the immune system is still holding up to stop us getting severe disease."
He then offered an analogy by way of explanation: "It's like a deck of cards and it keeps getting reshuffled.
"An immune system can recognise the same cards, basically.
"So far the worry would be a new deck of cards might emerge, or a different kind of suit of cards might emerge, and then we might be in more trouble, but for the moment it's the same deck of cards being reshuffled basically."
The "slight concern" is the three extra mutations, which have previously never been identified in SARS-CoV-2, he said.
Prof O'Neill added that we can be optimistic that vaccines will prevent severe disease when it comes to Omicron XE.
He said that vaccines that can be effective against every emerging variant are in development and will be "the real dream" in tackling coronavirus.
"There is a huge amount of effort going in to try and make them," he said.
"People probably don't realise that there is still a frenzy of activity around making new vaccines - next-gen vaccines they are called. Some of them are even better than the current vaccines.
"There are 130 vaccines in development, so keep a close eye on that one as well."
However, as Covid is a respiratory disease, another spike in cases is likely in the autumn after infections subside over the summer months.
Prof O'Neill said: "Come September, October there's bound to be a surge because we're back indoors again. I
"'m keeping my fingers crossed that these next-gen vaccines will be rolled out as soon as we possibly can, otherwise there could be problems with these new variants that keep emerging."
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