Booster vaccines could give people two to three years' protection from COVID-19, according to Professor Luke O'Neill.
He says third shots are leading to a "huge" immune response and give people very strong protection against serious illness.
Ireland's booster campaign has been getting underway, with healthcare workers, over-60s and vulnerable groups set to get a third dose of a vaccine over the coming weeks and months.
Other countries such as Israel have already started population-wide booster campaigns.
Professor O'Neill -Professor of Biochemistry at Trinity College - told The Pat Kenny Show we're now getting lots of data about how well the extra doses are working.
He said: “This is a huge study from Israel - 1.15 million people. A huge number of people were followed after the booster shot.
“There was huge protection after the third shot - 93% protection against severe disease, and 92% against hospitalisation.
“The unboosted ones, who they had as a kind of control group... they had a higher risk of hospitalisation.
“What’s happening is the booster is restoring protection back to what it was.”
Professor O'Neill said the immune response is so strong it could give people two to three years' protection.
He also believes three shots will become the norm for anyone receiving a COVID-19 vaccine for the first time.
He observed: “After Christmas, I predict, anybody getting a vaccine from the start will be given three shots - this will become a three-shot vaccine, and that will constitute full vaccination.
“It's working so well... you’d be foolish not to give the third shot, given it’s causing a huge response.”
One of the concerns around booster campaigns is that many people in developing countries remain unvaccinated, with the WHO saying it's vital to get more people vaccinated before population-wide booster campaigns begin.
Professor O'Neill suggested the supply is now there to get vaccines to more and more people - but the mission is to get that supply to developing countries and into arms.
Boosters also mean many people will be getting a different vaccine from their original dose, with anyone who received the AstraZeneca vaccine in Ireland set to get a Pfizer or Moderna jab for their third shot.
Professor O'Neill said "all the data" now supports using the mRNA vaccines as boosters for those who've previously received AstraZeneca.
However, he noted that the latest research shows there's only a "slight difference" between the vaccines in terms of how quickly they wane after a second dose.