New data from Johnson & Johnson has shown it has seen a good response to all COVID-19 variants.
It comes as younger people will be able to receive a Johnson & Johnson vaccine in pharmacies from Monday.
Health Minister Stephen Donnelly earlier confirmed the "significant acceleration" of the vaccine programme.
Luke O'Neill is professor of biochemistry at Trinity College Dublin (TCD).
He told The Hard Shoulder the drug even seems effective against the new Epsilon variant.
"They released information yesterday, saying that they're getting a good response to Delta with the single-shot J&J vaccine, which is great.
"They've been measuring people over the course of several months since they've had the one shot.
"Immunity grows and grows over time, first of all, secondly good anti-body response against Delta, good T-cell response.
"They're the two bits of the immune system you want to help you - it's really good news.
"And now of course as we've seen, the 18 to 34-year-olds will have the option of getting that vaccine from July 12th."
'Boosters in the winter'
Prof O'Neill says he has seen a Johnson & Johnson publication, which contains more good news.
"They're getting a good response to all the variants.
"They gave the vaccine to people and then they took blood from them, and then tested antibodies in their blood against multiple variants - including Epsilon, the new one [that] might be coming down the track.
"It was slightly less powerful than it was against other ones."
Prof O'Neill says second shots are not needed so far.
"One of our concerns was they'd need a second shot, because obviously Johnson & Johnson's a single-shot vaccine, and yet that single shot seems to give you eight months at a minimum.
"Now they only have eight months worth of data, I suspect it'll go on for a year or more protection".
But he adds: "I predict there will be boosters in the winter for old people and vulnerable people - that makes sense at this stage of it."
And he has this advice for people: "Get into your pharmacy, it's very convenient.
"The pharmacists have 60,000 doses of Johnson & Johnson and 70,000 coming in.
"That will give you protection and it'll stop the virus spreading in the community".