The Government controversially departed from public health advice for the first time to reject a move to level five of coronavirus restrictions, instead moving to level three nationwide.
Mr Donnelly has insisted that this was the “best decision” for the country.
But the move is said to have angered officials at the National Public Health Emergency Team (Nphet), which has warned that intensive care units will become overwhelmed.
Currently 243 out of 281 intensive care beds are occupied, leaving just 38 available.
However Minister Donnelly has insisted that hospital services can cope.
He told RTE’s Morning Ireland: “The surge capacity that the HSE can bring online quickly is north of 300 ICU beds.
Over a two-year period, we’re looking for a very substantial increase.
“But lets remember that at the very height of this, when there were many more people in hospital, and many times more ICU admissions, we didn’t come close to needing the kind of ICU capacity that the HSE had put in place.
“Of the tragically many men and women that have lost their lives to this virus in Ireland, a very small percentage of them ever go anywhere near intensive care.”
Mr Donnelly said he had spoken with HSE chief executive Paul Reid about the issue, who told him he believes there is sufficient capacity in ICU beds.
Asked if he would take responsibility if the decision to depart from public health advice proved to be wrong, Mr Donnelly replied: “It’s not about who’s right and who’s wrong.
“It’s about trying to make the best decision we can given the evidence we have.”
This graphic gives a quick and handy overview of Level 3. For more info, see https://t.co/O1sRmN9X4b pic.twitter.com/IVbeNfGQsm
Advertisement— Stephen Donnelly (@DonnellyStephen) October 5, 2020
The Minister said the situation had changed since March and that there were other factors to consider other than the suppression of the virus.
“If we needed to consider nothing other than the suppression of the virus, if we didn’t need to consider the entire of the country, then clearly one could make an argument that says well everyone just needs to go home, close down businesses, don’t leave your house.
“And obviously we know that the virus would be suppressed.
“But we have to make what we believe is the best decision on behalf of the entire country, that is what we have done.”
He said that level three measures have been shown to work “when we all work hard to put them in place”.
Meanwhile Sinn Fein president Mary Lou McDonald has criticised the Tanaiste over comments he made about Nphet.
She accused the Government of “answering back” to Nphet and said Leo Varadkar had “squared up” to Chief Medical Officer Dr Tony Holohan in his comments on Monday night.
Mr Varakdar had said that Nphet’s recommendation to move to level five “had not been thought through”.
Ms McDonald said the advice was given in “good faith”.
“I don’t think the Government should be ‘bounced’ into anything, but I don’t think it’s fair that a body that is specifically charged to provide you with best medical and scientific advice to then accuse those people of attempting to bounce you,” she added.
Under level three restrictions people will be asked to remain in their county and can have up to six visitors from just one other household.
Indoor gatherings will be banned, but pubs and restaurants will be allowed to remain open but with additional restrictions.
