The Tánaiste says the reopening options available to the Government were to develop a "corona pass" or keep indoor activities closed until the country reaches herd immunity.
Leo Varadkar has been defending a controversial proposal to only allow fully vaccinated people or those who've recovered from COVID-19 to dine indoors.
He says it would allow for other indoor live events as well, and mean no lockdown if there is a fourth wave of COVID-19.
Mr Varadkar and other ministers are meeting with the hospitality industry later today, following the Cabinet decision to delay reopening by at least two weeks.
The proposals around the vaccine pass have been criticised by both the industry and opposition parties.
On Newstalk Breakfast, the Tánaiste insisted there were only two options available to Government.
He said: “We can use those three weeks to develop plans for a corona pass, which let’s not forget may pave the way for the reopening of not just indoor hospitality but indoor sports and live events [as well] even if there is a Delta wave.
“That’s one of the things that maybe isn’t fully understood about the decision and advice from yesterday. Option one is to not reopen indoors until we have herd immunity - and who really knows when that will be. We’d hope it would be September, but maybe not.
“Now we have this option to use a corona pass… and potentially never having to lock down again."
Mr Varadkar acknowledged such a pass was something the Government had previously ruled out and that "lots of people will be against this".
However, he said they're now faced with a "different decision" due to the increasing concerns about the Delta variant.
He accepted Ireland's an outlier in Europe in terms of the speed of reopening, suggesting: "It will play out now over the next couple of weeks as to whether we've been too conservative or not.
"What happens in England and Scotland will tell us a lot. But bear in mind the ECDC is saying what NPHET's saying - that there is going to be a wave of Delta across Europe, and it is going to be serious.
"I hope we're wrong, by the way - I hope we're being too cautious, and NPHET's projections are too pessimistic. If they are, we can change."
The Tánaiste said the Government didn't know how stark NPHET's models about a potential surge of the variant would be until they saw them on Monday - saying they came as a "big surprise".
He said: “We asked them to do the modelling quickly to get the advice to us quickly so we could make a decision earlier than planned.
"That was part of the reason why I think it was so rushed - they’re not entirely to blame for that, [and] I don’t think the result would be different."
Mr Varadkar said everyone knew in the last week or so that the idea of a "delay of two or three weeks was being suggested".
He added that he's as "disappointed as everyone" that reopening can't go ahead as planned on July 5th.
The Tánaiste said he's hopeful to vaccinate people "much quicker" than the current target of vaccinating all adults by the end of September.
He said the current target is around 12 weeks away, but he hopes the latest advice around vaccinating younger means that timeline could be reduced.