Prime Minister Giuseppe Conte announced the closure of all non-essential factories in a late-night TV address on Saturday.
The Mediterranean nation of 60 million people is now the epicentre of the disease, which first emerged in central China late last year before marching out to the rest of the world.
Italy has now reported more deaths than mainland China and third-placed Iran combined, and it has a death rate of 8.6 per cent among confirmed Covid-19 infections – significantly higher than in most other countries.
Across the Atlantic, more than a third of Americans were adjusting to life in various phases of lockdown, including in New York, Chicago and Los Angeles – the three biggest US cities. Other parts of the United States are expected to ramp up restrictions as well.
“This is a time of shared national sacrifice, but also a time to treasure our loved ones,” US President Donald Trump said. “We’re going to have a great victory.”
As world leaders have vowed to fight the pandemic, the number of deaths and infections has continued to rise, especially in Europe – the main global hotspot.
Spain reported a 32 per cent spike in new deaths on Saturday, and Prime Minister Pedro Sanchez warned in a TV address that the nation needs to prepare for “very hard days ahead”.
Fatalities in France jumped to 562 as police officials said helicopters and drones were being deployed to boost the government’s attempts to keep people in their homes.
The unprecedented measures to counter the spread of Covid-19 have shredded the international sports calendar, and pressure is mounting on Olympic organisers to postpone the 2020 Tokyo Games.
The pandemic has bludgeoned global stock markets, and the United States – the world’s biggest economy – is preparing a huge emergency stimulus package that could top $1 trillion.
Millions have been ordered to stay home in the United States.
New Jersey on Saturday followed several states in telling residents to stay indoors. Governor Phil Murphy ordered all non-essential businesses to close their physical stores from 9pm (0100 GMT Sunday).
And in neighbouring New York, Governor Andrew Cuomo warned that the disruption is likely to last for months, not weeks.
“I don’t think it’s possible in a city of this size for people to maintain it for much longer than three weeks before they start losing it,” Yona Corn, a 35-year-old singer, told AFP.
“I think there’s going to be a big mental health crisis. I worry about what’s going to happen to people.”
Congress members are hoping to agree on a $1 trillion emergency aid package as fears grow about the economic falling-out from the crisis.
The US Food and Drug Administration also approved the first coronavirus test that can be conducted entirely at the point of care for a patient – and deliver results in 45 minutes.
Vice President Mike Pence and his wife tested negative for the coronavirus, his press secretary tweeted Saturday. The couple had taken the test after one of Pence’s staffers contracted the illness.
The drastic confinement measures follow the example of China, where the lockdown of Hubei province appears to have paid off. Wuhan, Hubei’s capital, is where the virus was first detected.
China reported its first local infection in four days on Sunday. While the number of cases in the mainland has slumped dramatically since the crisis began, there are fears of “imported” cases from other hotspots like Europe.
France, Italy, Spain and other European countries have ordered people to stay at home, threatening fines in some cases, while Australia on Sunday told citizens to cancel domestic travel plans.
Britain has told pubs, restaurants and theatres to close and warned citizens to stop panic-buying.
And India went into lockdown on Sunday with a one-day nationwide “self-imposed curfew”.
While the elderly and those with pre-existing medical conditions are the hardest hit by the virus, the WHO has warned that young people are also vulnerable.
Accurate Covid-19 figures are difficult to reach because many of the victims suffered from other illnesses, and infection rates are uncertain because of a lack of testing in many countries.
The coronavirus has infected more than 1,000 across Africa too, where healthcare systems are limited and social distancing measures – like the ones being adopted in North America and Europe – are difficult in crowded cities.
The Middle East also remains on high alert, where Iran – which suffered a major outbreak – reporting 123 new deaths on Saturday. But the Islamic Republic has refused to join the rest of the world in imposing heavy restrictions.