The Tánaiste says the impact of the Covid-19 vaccine won't be felt until at least next April.
Leo Varadkar told his parliamentary party last night there's a good chance the first jabs will happen before the end of this year.
The green light for the Pfizer vaccine could be given by the European Medicines agency as early as next week.
But Dr Lara Dungan, a leading immunologist, says there will be no St Patrick's Day parade next March.
"I think that realistically the first people will start getting vaccinations maybe just before the start of the new year in Ireland, but I wouldn't be breaking my heart for that.
"I think it will take months and months before we get everyone done.
"I don't think that we're going to have a normal March - I don't think we're going to have a St Patrick's Day parade.
"This isn't the kind of thing that's going to happen instantaneously, but hopefully by the end of 2021 our population should be vaccinated."
