Professor Sam McConkey says everyone in Ireland will need a booster against COVID-19, but we should wait for the 'next generation' of vaccines.
It comes as healthcare workers are due to start receiving their booster jab this weekend, after the National Immunisation Advisory Committee (NIAC) approved it.
Those over-60s are also in line for a booster.
Prof McConkey is head of the Department of International Health and Tropical Medicine at the Royal College of Surgeons in Ireland.
He told Newstalk Breakfast everyone will need one eventually, but it may be better to wait.
"I think we all will need one - it's very analogous to the flu vaccine that many of us get every year.
"The coronavirus, as we've all heard, keeps changing: it started off in January 2020 that it was was one version, then we'd an Alpha variant, then we'd a Delta variant, now we've the Delta Plus variant.
"Unfortunately that pattern of gradual change is going to continue.
"So I suspect we won't need a booster of the current vaccine, it'll be the next generation vaccine that many of us may need.
"And there be some advantages to waiting for the next generation vaccines - rather than getting third, fourth, fifth sort of super-boosters of this one - as I know some people have been calling for."
He says the newer version of vaccines from drug-makers take account of other variants.
"They're watching each new variant of interest... and as soon as they see it, and have the genetic sequence, are making the basic ingredients for new generation vaccine in case that particular variant becomes the one that we're all dreading - this new variant that spreads in currently vaccinated people.
"So it's likely that, just like influenza, you get a slightly different influenza strain coming to get us - that it'll probably be a different strain next year and a different strain the year after".
"And if you're over-vaccinated against the first strain, it can make it harder to change the immune system - in some cases - to be effective".
He adds: "I feel the most important role for vaccination now is that people who've not yet had any vaccine do still come forward and get one".
Prof McConkey says about "10,000 people a week" have come forward in the last few weeks.
