Higher Education Minister Simon Harris has said questions around mandatory hotel quarantine need to be asked before it is expanded.
He was speaking as plans to increase the number of countries on the quarantine list could face legal difficulties following a warning from the Attorney-General.
The Department of Health is considering adding countries including the US, Italy, Germany and France to the list in the coming weeks.
The Travel Expert Advisory Group has advised Health Minister Stephen Donnelly to change the criteria for the system to include countries that have high levels of the virus.
The system was previously aimed only at countries believed to be harbouring new variants.
Minister Harris told The Hard Shoulder while he believes in the system, there are issues that need to be ironed out.
"You could have a number of Irish people abroad, they could have been vaccinated already, do they need to mandatory hotel quarantine?
"You could have a student who's on Erasmus in France who's had a negative test before they've left France, and has a spare room in the family home to isolate in for the two weeks.
"I suppose some of the questions that I think we do just have to ask is what about vaccinated people, and also what about our own citizens returning?
Giving an example of a student returning from abroad, who may not be able to pay for hotel quarantine, he said: "There are just a couple of logistical questions that I think makes sense to thrash out before we actually announce these things."
He said a consultation between Minister Donnelly and Foreign Affairs Minister Simon Coveney is now underway, with an announcement expected on Tuesday.
"The law that we passed in the Oireachtas does say that the Minister for Health does need to formally consult with the Minister for Foreign Affairs.
"I think it's really regrettable that this leaked in advance of that consultation taking place - because what drives the public mad are half-baked announcements."
He said while the system has a place, it needs to be credible.
"I really do believe in the concept of mandatory hotel quarantine but... the environment in which we introduced it now is changing and changing fast.
"Are we genuinely saying that if an Irish person, a citizen in our own country, is returning and is fully vaccinated from COVID, do they have to actually quarantine?"
"I think these are the legitimate questions that my colleague, the Minister for Foreign Affairs, and others - and I think Irish people in general - will be asking."
"Mandatory hotel quarantine has a massive role to play, I'm delighted it's up and running, more countries will be added to the list - but I think it does make sense to bottom out some of these things for the system to have credibility".
Later on Thursday, the Government added 26 countries and states to its mandatory hotel quarantine list.