President Donald Trump summed it up pretty well in one of his more lucid moments sat alongside Leo Varadkar in the Oval Office on Thursday.
"It is pretty amazing when you think of what happened and how fast this spread to the world," he said.
"It was one country, then it was four countries, then it was nine - I am reading this list every week - then it was 13, then it was 22 and now I guess it's over a hundred countries.
"So I guess it's an amazing thing how fast this one spreads. This is a very fast spreader."
This was the week when "the fast spreader" changed everything. Rarely does a story have such global reach and consequences. The last time was the financial crisis in 2008 but the impact of the coronavirus will be much greater.
No one knows where and when it will end and how many people will die. This is the terrifying reality confronting us all now.
In the United States, the public attitude shifted as the week progressed from disturbing local TV news stories in New York about fake hand sanitiser burning its users to the front page of 'The Washington Post' yesterday screaming: "Outbreak begins to upend life across US."
It relegated the annual St Patrick's Day celebrations by Irish-American politicians and business leaders to a mere footnote.
Several events were cancelled, and those that did go ahead were more poorly attended than in previous years. People reluctantly shook hands, awkwardly elbowed or stood blankly staring at each other.
Speaking on the margins of one such event, a St Patrick's Day business lunch in Washington DC, Tourism Ireland chief Niall Gibbons painted a stark picture of the impact already being felt in his industry. "We have seen some enterprises let people go already. It is an industry that depends on the demand pipeline, particularly in the corporate sector, has dried up. Bookings have dried up in the leisure sector as well," he said.
The Taoiseach cancelled events in New York, where UN ambassadors were treated to a special performance of Riverdance at Radio City Music Hall on Tuesday night as part of the Irish Government's final push for a seat on the UN Security Council next year.
Had the event been due to take place later in the week it probably would have been cancelled. Some attendees wore face masks and gloves and there were plenty of empty seats.
Mr Varadkar's visit was cut to 24 hours of events in Washington which themselves were overshadowed by the crisis as it unfolded.
He was whisked away early from the Ireland Funds dinner on Wednesday night after Mr Trump announced a unilateral ban on travel from several European countries but not Ireland, it was later clarified.
The dinner itself was not as well attended as in previous years and emptied early as guests were treated to a mediocre musical performance from former New York congressman Joe Crowley who is best known for being ousted by Alexandria Ocasio-Cortez, the rising star on the left of the Democratic Party.
Mr Varadkar's departure was as much to get an update on the ban as it was to consult with public health officials and Government colleagues at home on the extraordinary emergency measures he would then announce as dawn broke in the US capital on Thursday morning.
Assurances offered by political leaders can only go so far and some have criticised Mr Varadkar's decision to announce the emergency measures while being almost 5,000km away from home.
But to his credit he was the personification of cool, calm and confident leadership on the third occasion in which he has sat alongside Mr Trump in the Oval Office. This was undoubtedly his most assured performance yet on this global stage - a far cry from the gaffe-laden first trip where he boasted of having helped Mr Trump on a planning issue for his Doonbeg golf course.
He methodically outlined the drastic and unprecedented measures Ireland was taking to combat the spread of the coronavirus when he was briefly given the floor by Mr Trump.
"We've acted just as you've acted decisively in the last couple of days," he said.
"Right, sure, sure," said the president, feigning interest before he spent the next 25 minutes doing most of the talking. Mr Trump downplayed the sinking markets and insisted that testing for the coronavirus was going well - putting him at odds with practically every elected American official.
He defended his unilateral ban on travel from 26 European countries, bitterly noting: "When they raise taxes on us they don't consult us."
And then, in trademark fashion, boasted that the US does not have as many deaths as other smaller countries that "have many, many deaths".
"I think it'll go pretty quickly. Stay away from people and wash your hands and do all the other things that we're supposed to be doing," he said. "I am not concerned."
His response couldn't have been more unsettling as journalists in the Oval Office wondered whether they may be at risk given the president came into contact with an aide to Brazilian President Jair Bolsonaro last weekend who was since reported to have tested positive. Mr Bolsonaro denied reports yesterday that he too had tested positive. Mr Varadkar will perhaps be relieved that he didn't shake hands with the president.
Back at home, ministers cancelled their St Patrick's Day plans altogether, including Simon Coveney, Michael Creed, Heather Humphreys and Ciaran Cannon, who were all due in the US. Defence Minister Paul Kehoe is already in Savannah, Georgia.
Elsewhere, Justice Minister Charlie Flanagan cancelled a trip to Germany this weekend and Culture Minister Josepha Madigan will not travel to London. "The virus takes precedence over everything," said one Cabinet minister.
It will be like that for a long time to come.