The roll-out of the Pfizer/BioNTech Covid-19 vaccine could begin in less than a week as a consignment with enough to give up to 9,750 people a first dose may arrive as early as Saturday.
It follows the decision yesterday by the European Commission to grant the vaccine conditional marketing authorisation following a recommendation by the European Medicines Agency (EMA).
It paves the way for Pfizer to transport two shipments to each member state in time for the EU-requested roll-out to begin on Sunday.
Each country will get two shipments from the Belgian plant initially, each with 4,875 doses, before larger amounts are delivered according to a nation's population later next month.
The first to be offered the vaccine here will be people aged over 65 in long-term care and frontline health workers.
Each person must receive two doses three weeks apart.
It will take months for all 2.3 million doses to arrive here.
It is expected the HSE will use up all the initial doses and wait for further deliveries to give people their second jab.
"Thiss announcement marks a significant moment in the fight against Covid-19," said Paul Reid, country manager with Pfizer Healthcare Ireland
"This authorisation is a goal we have been working toward since we first declared that science will win, and we applaud the European Medicines Agency and the European Commission for their ability to take timely action to help protect the people of Ireland."
Irish-born Emer Cooke, the executive director of the EMA, said: "We have achieved this milestone thanks to the dedication of scientists, doctors, developers and trial volunteers as well as many experts from all EU member states.
"Our thorough evaluation means we can confidently assure EU citizens of the safety and efficacy of this vaccine and that it meets necessary quality standards.
"However, our work does not stop here.
"We will continue to collect and analyse data on the safety and effectiveness of this vaccine to protect people taking the vaccine in the EU."
The vaccine can be given to people over 16 and also offered to pregnant women on a "case by case basis".
The EMA said the Pfizer/BioNTech vaccine trial showed it was around 95pc effective in preventing severe illness in people infected with the virus, including those with asthma, chronic lung disease, diabetes, high blood pressure and obesity.
The most common side-effects were usually mild or moderate and subsided within a few days.
They included pain and swelling at the injection site, tiredness, headache, muscle and joint pain, chills and fever.
There has been a very small number of allergic reactions to the vaccine and based on these people will be closely observed for at least 15 minutes after getting the shot.
Pharmaceutical companies will send monthly updates on new findings as opposed to the normal schedule of six months.
The EMA has also commissioned its own independent scientific studies to monitor the safety of the vaccine in its real-life application.
Asked about the new strain of Covid-19 which is said to be much faster spreading, the EMA team said the vaccine was likely to offer protection against this new variant.
Health Minister Stephen Donnelly yesterday welcomed the green light for the vaccine saying it was great to be moving into 2021 with wonderful news.
He said detailed plans were in place for the roll-out with the most vulnerable prioritised.