Minister for Health Stephen Donnelly has authorised the use of booster vaccines for healthcare staff.
Following new advice from the National Immunisation Advisory Committee (NIAC), around 270,000 frontline health staff will now receive booster Covid-19 vaccines.
Minister Donnelly said he had asked the Health Service Executive to prepare for a programme some time back and has now asked that it be rolled out.
The vaccines will begin to be administered this weekend.
The mRNA vaccine boosters will be given to health staff around six months after they completed their original vaccination.
Pfizer and Moderna vaccines will be used, regardless of what initial vaccine health staff received.
Minister Donnelly said: "I received the NIAC advice just in the last few hours. We've been working hard with the HSE in the background to be ready should we receive this advice.
"In further good news, the HSE advises that it believes it will be ready to begin administering these booster vaccines to healthcare workers this coming weekend."
Up to 3,500 health staff are currently absent from work because of Covid-related illnesses.
The General Secretary of the Irish Nurses and Midwives Organisation said she is "delighted that the decision has finally been made" to offer booster vaccines to healthcare workers.
Phil Ní Sheaghdha said "what we need now is an immediate roll-out of the booster for healthcare workers because we can't sustain 400 infections per week" among healthcare workers.
She said the INMO has been writing to NIAC, Government ministers and the HSE for the past month "because we've watched the figures and the infection rates increase".
"We know that the immediate brace now is to get the vaccine and the booster administered as quickly as possible. The HSE tell us they're ready to go. That's good."
Ms Ní Sheaghdha said "we have to make sure that staff, who are going to be working in what is now an extremely overcrowded hospital system over this winter, are supported to stay at work no matter what that takes".
Dr Anthony O'Connor, a member of the Consultant Committee of the Irish Medical Organisation, said "we're very pleased about it, it's the news we've been looking for".
The Consultant Gastroenterologist at Tallaght University Hospital in Dublin said "over the last few weeks in particular, we've had huge difficulty in maintaining adequate staffing numbers because of people going out with Covid".
He said "there are also issues around people waiting for tests and there are also people having to care for family members who might be off sick with Covid".
"So this is a start. We look forward to working further with the Government to see how we can keep as many of our healthcare team as possible on the frontline this Christmas."
Asked about the timing of the NIAC decision, Dr O'Connor said: "There's never a wrong time to make the right decision and hopefully we'll be seeing the benefits as we go on into winter."
Sinn Féin Spokesperson on Health, David Cullinane, welcomed the announcement but warned that the Government must take further steps to support healthcare staff.
"Crucially, we also need to see the Government publish a detailed timeline setting out when and how they will ensure safe staffing levels are secured in our hospitals."
He said his party will put forward a Dáil motion tomorrow on a number of issues, including a "fair pay allowance" for student nurses and midwives.
Earlier today, the first healthcare worker in the State to get vaccinated said she and her colleagues were concerned that their vaccine protection was waning.
Bernie Waterhouse was vaccinated on 1 December 2020 and her colleagues were vaccinated shortly afterwards.
Speaking on RTÉ's Today with Claire Byrne, Ms Waterhouse said she would like NIAC to make a quick decision on whether booster shots should be rolled out to healthcare staff.
Ms Waterhouse, who has been working on Covid wards throughout the pandemic, said the experience has had a significant impact on staff.
She said the team was physically and emotionally exhausted, with many attending counselling as a result of their experience.
Ms Waterhouse added that many nurses had just qualified and their only experience of nursing has been Covid, which is a very difficult start to a career.
"The amount of deaths they've seen, the quick deterioration of patients is very harrowing on them," she said.