The Tánaiste, a qualified doctor, tweeted a short video entitled ‘Antigen tests are easy to use but it’s important to use them right’.
He then offers an "explainer" alongside the hash tags #whentoantigen and #protectourprogress.
However, one reply simply stated: “Snake oil salesman as per @CMOIreland”.
While another user writes: "It's either one or the other ...why throw confusion into."
The comments is a reference to Dr Philip Nolan, who said on Twitter last April that antigen tests were ‘snake oil’.
One of Nphet’s most high-profile people, Professor Nolan had tweeted: “Can I get some snake oil with that? It makes for a great salad dressing with a pinch of salt and something acerbic.
"Stay safe when socialising outdoors over the next few weeks. Small numbers, distance, masks. These antigen tests will not keep you safe.”
He later admitted that this was not the “wisest” thing he had ever tweeted.
However, many members of Nphet, including Chief Medical Officer, Dr Tony Holohan, as well as Dr Nolan, the expert medical group’s head of modelling, have long been against the tests being part of the wider toolkit to tackle the pandemic.
Their stance was criticised by Professor Luke O'Neill, who said at the time: “I know lots of doctors and they can be very cautious, especially in public health you see, because they’re trying to protect people, that’s one possible reason for this.
“And it was a bit complicated because you had to tell people certain things.
“One of the things was, if you’ve symptoms, don’t use the test, that seems counter-intuitive, so again, Tony (Dr Holohan) was reluctant, and that’s understandable.
“But overall I feel we should have got the message out very clearly that these are very useful and here’s the way to use them and I would have done that three, four, five months ago really.”
He added: “It’s certainly not snake oil.
“I feel a bit sorry for Philip (Nolan) there because he was actually answering with a barbeque pack with an antigen test and he was doing it that way, so he was badly caught wasn’t he?
“And I’ve been caught myself.
“But no, it’s not snake oil, I mean the technology is fantastic.
In response to Mr Varadkar's "explainer” other people took him to task with one writing: “Cool, now if you could subsidise them so I can actually find affordable ones that would be great.”
Another added: “These tests should be free of charge...don't know why you've had to explain what we have to pay for.”
However, some supported the Tánaiste, with one saying: “As a qualified GP I reckon he is trying to be helpful”.
Another added: "Great video. Thumbs up many people doesn’t know to use it; demonstration will certainly help. India got the #OmicronVarient and that too in our State, two confirmed cases from Bangalore, one has travel history from S. Africa, maybe third wave knocking at our door. Stay safe everyone!!”