Immunologist Luke O’Neill says it is almost impossible to avoid the latest strain of COVID-19.
The sister variant of Omicron, BA.2 is understood to be 30% more virulent than Omicron, which itself was 70% more contagious than Delta.
There are 1,338 people in hospital with the virus today in Ireland, up 30 on yesterday, with 61 patients in ICU.
Speaking on RTÉ Radio 1's Claire Byrne live, Luke O'Neill said the new variant is possibly "the most infectious we've seen."
He continued: "This BA.2 there’s nothing like it, it’s 30% more infectious than Omicron, which is already 70% more infectious than the previous one. A great phrase I saw this morning is 'BA.2 is sweeping up everyone who didn’t get Omicron”. In other words it’s almost impossible now to avoid this really."
Mr O'Neill's comments come as a Co. Monaghan doctor claimed there's a growing reluctance among the general public to test for Covid-19, which in turn is contributing to rising infection rates.
Dr Illona Duffy says 60% of patients at her clinic say they've had Covid in the past few weeks, however, official daily figures have remained stagnant over the period at between 12,000 and 14,000.
The INMO has called for the reintroduction of mask-wearing in crowded and indoor settings, despite calls from Leo Varadkar that the government has had no public health advice to make masks mandatory again or reintroduce restrictions.