The country faces a nationwide lockdown at Christmas unless stricter measures are introduced in the face of surging coronavirus cases, health experts have warned.
Nationwide Level 3 restrictions, introduced in a bid to reduce rising levels of infection, will only serve to level the numbers off and not drive them down, said Professor Anthony Staines, the head of Health Systems at DCU.
"We need to go to Level 4 today," he said.
"Looking at the Dublin figures for the last few days, the numbers have stabilised so it seems likely that what we are doing at the moment will hold things steady, but to push things down will take a sharper jolt.
"Every day you delay is a day added to the other end at least. If we are going to do this and give people a bit of hope for Christmas, we need to do it as soon as possible."
Prof Staines, who is part of the Zero Covid group, was responding to the government decision not to implement the Level 5 restrictions recommended by the National Public Health Emergency Team (Nphet) on Sunday night.
He said he agreed in theory with what Nphet had prop-osed, but Level 4 would be more appropriate.
"To bring numbers down to where they need to be, it's going to take something like three to four weeks of quite severe restrictions," he said.
"We would suggest Level 4 rather than Level 5 because it's less disruptive.
"A lot of small businesses close at Level 5 but they stay open at Level 4. What it will do is stabilise the number of infections and they will start to fall.
"We would estimate that maybe after two or three weeks you could see where you were and probably move to doing it by county. You go in and you change what you are doing in each county."
The major flaw with the Nphet proposal, suggested Prof Staines, was that there was no strategy to deal with what would happen after the period of Level 5 restrictions ended.
"To close everything that you possibly can and then just pray is not enough," he said.
"Nphet came up with Level 5, then for weeks Leo Varadkar had a very sensible question: 'And then what?' You then need responses in each county depending on what's going on, guided by local public health people."
Professor Gerry Killeen of UCC, who worked in Haiti during the Zika outbreak and has extensive experience of lockdowns, said the "time for half measures had passed" and Level 3 restrictions are not enough to deal with current trends.
"Right now we need to lock down hard," he said.
"We will find ourselves there sooner or later, but sooner is a lot better."