Professor Luke O'Neill says he's "delighted" antigen tests are finally going to be used widely in Ireland.
He said officials have "bitten the bullet" - but noted he still doesn't know why it didn't happen sooner.
It was announced earlier that close contacts of people who test positive for COVID-19 will now be sent antigen tests.
Anyone positive cases will be confirmed with a more sensitive PCR test.
Work will also get underway to see if the tests could help facilitate some events and activities.
It’s a significant change in approach from the Government, with health officials previously reluctant to roll out the tests more widely.
They’d raised concerns that the tests were less reliable than the ‘gold standard’ PCR test.
However, NPHET has now advised antigen tests should be used for fully vaccinated close contacts “given the high and increasing incidence of disease in the community”.
Luke O’Neill, Professor of Biochemistry at Trinity College, told The Hard Shoulder Ireland has “definitely” been an outlier when it comes to the use of rapid testing.
He explained: "Almost every European country does this - now in Ireland, at last, will see antigen testing widely, we hope.”
Professor O'Neill noted it’s already used in some countries to allow access to venues such as nightclubs - something he believes needs to be done here as well.
He also believes every household should be sent around a dozen tests, so people can test themselves before they head out.
Ireland 'behind the curve'
Professor O'Neill said Ireland’s been “really behind the curve” with rapid testing, while the likes of the UK (where the tests are described as lateral flow tests) have been using them as a key tool for months.
The leading immunologist said the tests should be given free to households here.
He said: “This is phase one I’d imagine - they should be widely distributed.
"They should have done it by now - they knew October 22nd was coming, and it’s a mystery to me why they didn’t do this a month ago. At last, they’ve bitten the bullet.
“The Taoiseach himself said yesterday he liked them, so that’s a very good sign. They’re listening, at last.”
Professor O'Neill stressed antigen testing alone is not a sufficient way to stop the virus in the community, but they are “yet another weapon to use against this virus”.
He suggested that even if antigen tests pick up just half the positive cases, that means those people won’t go out and further spread the virus.
He noted: “Nothing is 100% certain in life or in COVID. Even if it’s partially effective, it’s another weapon to use.”