On Monday evening, the Cabinet's powerful sub-committee on Covid-19 was presented with a series of slides by Professor Philip Nolan, Nphet's modelling expert, outlining how the vaccination programme could have a major impact on cases in the coming weeks.
With vaccination proceeding to schedule we could anticipate peak daily cases of 1,000-2,000 per day even with a very modest increase in close contact," the presentation states.
An accompanying graph showed a scenario where the reproductive rate of the virus, the R0, rises to 1.4.
Without vaccines, case numbers skyrocket to 6,000 and beyond per day by the end of May. But if the programme proceeds as planned - with one million doses a month being administered - then case numbers would peak at 2,000 per day before transmission starts being suppressed by the end of May.
The more dramatic impact of vaccination will be on hospitalisations. Even if the R0 reaches 2 - where every infected person infects another two people - weekly average hospitalisations would peak at 1,600 in mid-June, with a weekly average of 500 patients in ICU - a scenario not dissimilar to the third wave in January - before starting to fall in July, August and September.
All of this informed the government decision on Tuesday to begin relaxing restrictions cautiously from April 12.
While Nphet is sounding dire warnings about the risk of a fourth wave and warning the public to adhere to restrictions for the best part of the next two months, Taoiseach Micheál Martin was painting a more optimistic picture.
By the end of this month, we can expect to descend on zoos, wildlife parks and other outdoor attractions and the summer ahead looks rosy, with restrictions to be further reviewed before May.
Tánaiste Leo Varadkar has suggested the reopening of hospitality is on the cards for June. "As usual, Leo was trying to give more hope than Micheál," says one government insider.
Expectations have now been set that a competent vaccination programme will deliver the reopening of society before long. But the aforementioned insider noted that there was no real roadmap for May onwards, "just comforting words".
The optimism that may have been instilled by the government announcement waned as the week progressed, amid ongoing doubts about the competency of our vaccination programme and a row over mandatory hotel quarantine that has exposed a deeper rift in the Coalition.
The decision to change the priority list for vaccinations to jab people on the basis of their age and not their occupation has caused consternation among two key interest groups for politicians, teachers and guards.
The Fianna Fáil and Fine Gael parliamentary party meetings were rife with complaints from TDs on Wednesday.
The most serious row emerged in Fine Gael, where an unedifying spat between Varadkar and his one-time ally John Paul Phelan over the online meeting's chat function saw the Tánaiste accused of giving "tone deaf" answers. Phelan has become increasingly antagonistic towards his leader in recent weeks.
Fine Gael colleagues believe his grievances arise out of being dropped as a junior minister last summer when he was asked to drive to Dublin only to be told he was being offered the job of deputy whip, which he declined.
But he is not the only one of Varadkar's loyal leadership campaign allies whose stars have fallen. Eoghan Murphy and Joe McHugh - whose wife, former FG TD Olwyn Enright, advised the 2017 campaign - were dropped from Cabinet last summer. Former junior minister Michael D'Arcy's political career ended in controversy after he resigned his Seanad seat to take up a lobbying job he cannot start until later this year.
And as for Phil Hogan, the former EU commissioner is still deeply aggrieved by the manner in which Varadkar handled the fallout from Golfgate last August, precipitating his dramatic resignation.
Varadkar's perceived lack of loyalty to allies leaves him isolated within Fine Gael, with only a few colleagues performatively praising him at parliamentary party meetings these days.
Coupled with an ongoing Garda investigation into his leaking of a confidential government document, he is arguably as vulnerable in his position as Micheál Martin is currently in Fianna Fáil.
At the FF meeting on Wednesday evening, Martin had to contend with an ominous warning from backbencher John Lahart who said he hoped a successful vaccination programme would lead to a bounce for the country and Fianna Fáil. "I would have had Boris in mind," Lahart said this weekend of his comments at the meeting.
"But I said if there was a bounce for the country and not for the party that we would need to have a conversation."
Some anti-Martin plotters spoke this weekend of an effort by some of the Taoiseach's allies to provoke an early heave, whispering to the rebels that now could be the time to go while knowing full well that, at this stage, Martin would win a vote of his party. "It was fairly transparent," said one rebel who would prefer to hold out for the time being.
Such manoeuvres are of little interest to the public whose faith in the vaccination programme has been shaken by the Beacon Hospital scandal.
It is no laughing matter, which is why a tweet by one of Eamon Ryan's two chiefs of staff last week raised eyebrows in the Green Party. "Given my exalted status, somewhere between Captain of the Vanguard and Master of the Universe, it is now incumbent on me that I share any spare Covid Vaccines that come my way with my friends, you THE SOVEREIGN PEOPLE. Applications now open. Canvassing will kinda disqualify, a bit," Dónall Geoghegan, co-chief of staff to the Green Party leader, tweeted.
It was a joke, of course, but as one Green TD put it: "I really could do without jokes about people in high places messing with who gets the vaccine."
Public anger is also rising over mandatory hotel quarantine, which is fast turning into a debacle. It emerged on Tuesday that Health Minister Stephen Donnelly wanted to add 43 countries to the hotel quarantine list, including France, Italy, Germany and the USA.
But the leaking of the list drafted by public health officials prompted consternation in diplomatic circles and blindsided Foreign Affairs Minister Simon Coveney, whose department almost immediately began receiving calls from Irish diplomats in these countries wondering what was going on.
Attorney General Paul Gallagher wrote to Mr Donnelly to outline legal concerns about charging EU and Irish citizens for hotel quarantine. But it's unclear why such questions were not raised before.
The row has allowed some in Fine Gael to air their opposition to hotel quarantine - despite the party voting it through the Dáil in February. Former justice and foreign affairs minister Charlie Flanagan contacted this correspondent on Thursday to say it should be discontinued.
Even Varadkar himself was characteristically blunt in his assessment of the situation at his parliamentary party meeting on Wednesday, saying he had never been a fan of hotel quarantine, was never overly keen to introduce it and that one of the reasons he was so reluctant was that it would become very hard to remove it in the future.
He said Coveney shared his view and predicted the lack of any exemptions for elite sports people was going to be a major problem, in addition to there being no exemptions for healthcare reasons or essential workers.
Both he and Coveney last week appeared to be pushing to exempt the US and EU countries that public health officials and Donnelly want to put on the hotel quarantine list, amid concerns over the impact of thousands of Irish people living in Germany, France, Italy and elsewhere.
This reportedly led to a frosty meeting between Coveney, Donnelly and their respective secretaries general on Thursday. Sources close to both played down such suggestions. "It wasn't remotely frosty," insisted one Donnelly ally. "There was nothing frosty about it," a Coveney confidante said.
But both men are at odds this weekend, with some in Fine Gael believing Coveney is playing to the gallery. "There have been a fair few columns about him being irrelevant. It's probably doing him no harm," said one party source.
Donnelly has been hawkish on controlling overseas arrivals. Last summer, he tried to introduce a travel red list restricting arrivals from countries like Brazil and the US, but the proposal went nowhere.
This weekend, his allies say he is continuing to argue for all 43 countries to be put on the hotel quarantine list after he added 26 non-EU states on Thursday. "There is a strong public health rationale for it," says one.
On the other side, a senior Fine Gael source said they wanted the issue "walked through and thought through", suggesting the party would be happy to extend hotel quarantine even more widely if there were exemptions for people who are fully vaccinated.
Legally it appears Donnelly can press ahead with adding the remaining 17 countries to the list, but Varadkar and Coveney's desire to approach with caution when it comes to EU countries seems likely to win out. One senior Department of Health source admitted that one of the ideas being discussed is a separate and as yet undefined system for EU arrivals. Enhanced testing, including making the day-five PCR test mandatory, is also being examined, although the source admitted: "That's difficult because you can't force anyone to take a test."
This infighting serves only to make a nonsense of the current hotel quarantine system and does little to assuage public concerns about importing new Covid variants. It also exposes Coalition fault lines that ultimately hinder its response to Covid-19.
"Government looks weak and divided. The centre is still dysfunctional," one government insider observed. "This isn't working on any level."
