That equates to 37.4% of the country's total population.
The Taoiseach announced the figures in a tweet in which he also praised healthcare workers for their role in the vaccine rollout.
"Update on our vaccine rollout," he wrote. "Almost half (49.9%) of the adult population have now received a booster or third dose. That’s 37.4% of the total population. Great work by staff and volunteers in our vaccine centres, GPs and pharmacists."
Update on our vaccine rollout.
Almost half (49.9%) of the adult population have now received a booster or third dose.
That’s 37.4% of the total population.
Great work by staff and volunteers in our vaccine centres, GPs and pharmacists.
— Micheál Martin (@MichealMartinTD) December 23, 2021
The figures come as Health Service Executive CEO Paul Reid confirmed that Ireland is exiting the Delta wave and entering the Omicron wave.
Reid warned that the country could be facing 20,000 cases a day, though this could be combated by the booster programme and the following of public health advice.
The HSE CEO said that research is showing Omicron to be less severe but more transmissible than previous variants, with a transmission rate 5.5 times higher than Delta.
He highlighted that just 6% of the population have yet to receive their first dose of a vaccine, but the unvaccinated currently account for 54% of ICU patients. He urged unvaccinated people to come forward to receive the vaccine.