Getting the flu shot is more important than ever this year, as people have not been exposed to it due to COVID-19.
That's according to Luke O'Neill, professor of biochemistry at the School of Immunology at Trinity College Dublin.
Prof O'Neill, who's currently lecturing at the Norwegian Immunology Summer School, told Pat Kenny this is on the back of large outbreaks in Australia.
"The Australians are noticing a huge increase in flu - it's the winter there.
"There's a 10-fold increase in flu in Australia compared to last year.
"Will we get it in Ireland, is one question, and it's happening for definite.
"It seems to be because, of course, having been in isolation for two years - if you like - people are back out in the open again [and] they're picking up flu.
"And now it's becoming more severe in people."
He says the flu shot has been proven to work in the past.
"There's a 63% increase in flu week-on-week in New South Wales at the moment.
"What this means is get the flu shot, that's going to be the big watch, because the flu shots really work.
"So again as we move into the autumn in Ireland, like every year, the flu shot is recommended.
"But now more than ever it's important to have it, because people wouldn't have been exposed to flu in the past couple of years".
COVID booster mixes
Meanwhile, a new major study has found that any combination of coronavirus vaccines boost immunity.
The research involved some 100 million people who were analysed across 53 studies.
Prof O'Neill says the results were clear.
"The question is should you mix and match - for example, should you have three shots or two?
"And the evidence is compelling: three jabs are fantastically effective - 96% decrease risk of death and severe disease.
"Any combination works, [which] is the important thing.
"You can take one vaccine in three doses, or you can mix and match, and they all give the same effectiveness really.
"And that's important - of course - if we go to a fourth shot.
"Any fourth shot as a booster should work very well, so it's really important data".