The European Medicines Agency (EMA) has approved the Pfizer/BioNTech vaccine for children aged 12 to 15.
This the first green light for a vaccine for those aged under 16.
The drug is already being used for adults and adolescents aged 16 and above.
The EMA says the use of the Pfizer/BioNTech vaccine, also called Comirnaty, in children will be the same as it is in people aged 16 and over.
It will be given as two injections in the upper arm approximately three weeks apart.
The move follows a trial which showed that the immune response to the vaccine in this group was "comparable to the immune response in the 16 to 25 age group".
The efficacy of Pfizer was calculated in close to 2,000 children, aged from 12 to 15, who had no sign of previous infection.
Of the 1,005 children receiving the vaccine, and not a placebo, none of them developed COVID-19 compared to 16 children out of the 978 who received a dummy injection.
This means that the vaccine was 100% effective at preventing COVID-19 - however the true rate outside the study could be between 75% and 100%.
The most common side effects in children were similar to those in people aged 16 and above.
They included pain at the injection site, tiredness, headache, muscle and joint pain, chills and fever.
In a tweet, Health Minister Stephen Donnelly said the announcement was "very good news".
Very good news https://t.co/yaToWFKQNR
— Stephen Donnelly (@DonnellyStephen) May 28, 2021
A timeframe for Ireland's implementation of the vaccine changes is not yet known.