The wait time for a booster vaccine for those who've had Covid has been reduced from six months to three.
NIAC made the recommendation which has been accepted by the Government.
The HSE will now put the new advice into operation.
76,000 doses of Covid vaccine were administered yesterday.
Health Minister Stephen Donnelly said: "I welcome this update to our booster vaccination programme. As with the update to the programme I announced last week, decreasing the interval for booster doses in those who have had a breakthrough infection is an important step given Ireland’s current epidemiological situation.
"The emergence of Omicron has prompted this amendment, specifically the significant concerns we have about the risk of re-infection which is estimated to be approximately five-fold higher with Omicron compared to the Delta strain.
"Christmas week is an important time for many people as we look forward to seeing family and friends and taking a break at the end of a challenging year. This year, it is important that we take all the measures we can to break the chains of transmission from COVID-19. Each of us can take actions this week to protect ourselves and our loved ones, even if this means rethinking plans for the Christmas period, especially if you are not yet boosted or vaccinated.
"Yesterday, the HSE administered 76,000 doses of COVID-19 vaccines, the majority of which were booster doses. Please continue to come forward for your booster dose. Do not wait until after Christmas. You will be fully protected seven days after you receive your booster."
