A further 4,022 cases of Covid-19 have been confirmed by the Department of Health this evening.
530 people are in hospital with the virus, with 115 in ICU.
Chief Medical Officer Dr Tony Holohan said they have "confidence" that the Covid-19 booster gives "good protection" against the new Omicron variant.
He said this evening: "There are now six confirmed cases of the Omicron variant in Ireland. A number of other probable cases are under investigation.
"Although this is a new variant, our early understanding gives us confidence that a booster dose of COVID-19 vaccine will offer good protection against Omicron and Delta infection.
"Our current wave of disease continues to be driven by the Delta variant of COVID-19. We know that the public health measures we are so familiar with will break the chains of transmission of Delta, and we are confident they will work on Omicron.
"Please continue to layer up on the public health advice by getting vaccinated and boosted, reducing contacts, wearing masks, keeping distance, opening windows and cleaning hands regularly.
"It is heartening to see the large numbers of people who attended walk-in vaccination centres today to receive their COVID-19 booster dose as soon as it became available to them.
"If you are eligible for a booster dose, then please do not wait until after Christmas to receive it. You will begin to receive the benefit of your booster protection within seven days of receiving your third dose.
"This means that anybody who receives their booster vaccine this week or next can be confident in the protection the booster will offer as we move closer to the Christmas period.
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