A top Irish doctor has criticised Dr Tony Holohan and Professor Philip Nolan's "unfortunate" comments on antigen tests.
Liam Fanning, who is a Professor in Immunovirology at University College Cork, said he disagreed with the Chief Medical Officer and his NPHET colleague on the value of the tests.
Professor Fanning explained that, while not as sensitive as traditional PCR tests, antigen tests are best at detecting Covid-19 in people with a "high amount of virus".
However he stressed that anyone who is symptomatic should still be ringing their GP and booking a test.
He told the Irish Daily Mirror: "The best analogy I can think of is in a Corn Flakes box, at the top you have the big flakes and at the bottom you have small crumbs.
"PCR can detect the small flakes and crumbs, antigen tests can detect the big flakes.
"In virology terms, PCR can go down to much smaller levels of detection, but in many circumstances individuals who have very small amounts of virus are not infectious.
"These antigen tests are particularly good at picking up individuals who are infected and identifying those cases that are asymptomatic, who may not know they have a high amount of virus. That's where their value is."
And Prof Fanning went on to offer some advice to people looking to ensure they get the most accurate result possible from antigen tests.
He said: "The guidance is you should blow your nose beforehand to essentially clean out your nose and end up with a clean landscape and that you are not just sampling mucus.
"You have to put it up your nose and rub it against the surface of your nose, it's not just a matter of putting up into the space, you need to rub it against the cells that are on the inside of the antrum of your nose. And by doing that you are brushing off those cells so that if they are infected, and you have a large amount of virus, there will be enough virus trapped on the end of the cotton bud that goes into the solution, that then goes onto the antigen test.
"It is a little uncomfortable but it doesn't need to go up as far as the nasopharyngeal swab, which is way, way back.
"There are specific instructions though, you have to have a clean nose beforehand, and then you brush it against the cells which some might find a little uncomfortable but if you don't do that, obviously the test is less reliable.
"The NHS in the UK has a very good video on how to use these antigen tests and I suppose it's a pity the HSE hasn't come to a point where they have recognised the value of video education on how to use these things."
And Prof Fanning took aim at both Dr Tony Holohan and Professor Philip Nolan after their criticism of the antigen tests, with Prof Nolan comparing them to "snake oil".
Prof Fanning said: "I think both statements are very unfortunate, I'm not sure of the reasons for the vociferous nature of their comments, they have been rather forceful in their language in respect to their negative opinion on the value of antigen tests."
He continued: "I disagree with them. The Irish population is quite a bit ahead of those two particular individuals on the practicality and use of antigen tests. I think most individuals when using the antigen test, if they get a non-reactive test for Covid-19, they're not going to go wild I think
"There has been enough caution applied by the Irish public that they deserve a sense of respect that they can take responsibility for their own health and the protection of others by making use of these convenient home tests as opposed to the other processes that might not be so convenient, but they are only part of an army of tools.
"Bear in mind at the very beginning of the pandemic Dr Holohan wasn't quite so impressed at use of masks and their capacities, so nobody has a complete moral high ground on being right all of the time but I think in this regard both Prof Nolan and Dr Holohan's comments are most unfortunate."
