Spain joined Italy on Wednesday in seeing its death toll from the coronavirus epidemic surpass that of China, as more than a billion Indians joined a lockdown that has confined a third of humanity.
Markets rebounded after Washington vowed to spend $2 trillion to fend off a US economic collapse, while capitals elsewhere are still taking ever more dramatic steps to slow the spread of the disease.
"COVID-19 is threatening the whole of humanity -- and the whole of humanity must fight back," UN Secretary General Antonio Guterres said, launching an appeal for $2 billion to help the world's poor.
As of 1100 GMT on Wednesday, the number of deaths around the world from the new coronavirus strain stood at 19,246, with more that 427,000 declared cases registered in 181 countries and territories.
India's stay-at-home order is now the biggest, and Russia will follow suit, with President Vladimir Putin declaring next week a public holiday and postponing a public vote on constitutional reforms.
The G20 major economies will hold an emergency videoconference summit on Thursday to discuss a global response to the crisis, as will the 27 leaders of the European Union, the outbreak's new epicentre.
Spain saw the number of deaths surge to 3,434 after more than 738 people died in the past 24 hours, following Italy in overtaking the figure in China, where the virus originated late last year.
'People dying alone'
China has begun to relax its own draconian restrictions on free movement after reporting no new cases, and Spain announced a 432-million-euro ($467 million) deal to buy medical supplies from Beijing.
At the La Paz university hospital in Madrid, A&E nurse Guillen del Barrio sounded completely empty as he related what happened overnight.
"It is really hard, we had feverish people for many hours in the waiting room," the 30-year-old told AFP by telephone.
"Many of my colleagues were crying because there were people who are dying alone, without seeing their family for the last time."
Hard-hit Spain and Italy were joined by France and six more EU countries in urging Germany and the Netherlands to allow the issue joint European bonds to cut borrowing costs and stabilise the eurozone economy.
This is likely to fall on deaf ears when the 27 leaders talk on Thursday -- with northern members wary of pooling debt with big spenders -- but they will sign off on an "unprecedented" recovery plan.
Coronavirus cases are also spreading in the Middle East, where Iran's death toll topped 2,000 on Wednesday, and in Africa, where Mali joined all seven of its neighbours in declaring its first cases.
And in Japan, which has postponed this year's Olympic Games, Tokyo's governor urged residents to stay home this weekend, warning of a possible "explosion" of the coronavirus.
'Wartime level of investment'
The economic damage of the virus -- and the lockdowns -- could also be devastating, with fears of a worldwide recession worse than the financial meltdown more than a decade ago.
But financial markets soared after US leaders agreed a stimulus package worth roughly 10 percent of their economy, an injection Senate Majority Leader Mitch McConnell said represented a "wartime level of investment".
President Donald Trump has voiced hope the United States will be "raring to go" by mid-April, but his optimism appeared to stand almost alone among world leaders.
India ordered its 1.3 billion people -- the world's second-biggest population -- to stay at home for three weeks from Wednesday.
"To save India, to save its every citizen, you, your family... every street, every neighbourhood is being put under lockdown," Modi said.
Whether the order will be obeyed in full remained to be seen. Mumbai vegetable trader Rafiq Ansari said his customers were getting angry over shortages and price hikes.
"I don't understand what's going on," the 35-year-old told AFP. "We are going to face major shortages in the days ahead."
In China, authorities loosened tough rules on the 50 million people in Hubei province on Wednesday after a months-long lockdown as the country reported no new domestic cases.
The provincial capital Wuhan -- the ground zero of the outbreak after it was detected at a market that sold wild animals for human consumption late last year -- will allow residents to leave from April 8.
Iran's president said movement restrictions could be introduced as soon as Wednesday evening in the country, which has seen one of the world's highest death tolls, with 143 new deaths recorded overnight.
Meanwhile, nearly 130 million Americans, or 40 percent of the population, are under or will soon come under some lockdown order, including in the largest state of California.
Many governments are listening to health experts who warn the only way to slow the epidemic -- and save the lives of the elderly and vulnerable -- is by imposing "social isolation" measures.
Global markets have finally started to recoup some of the losses they have logged over a tumultuous few weeks.
Opening trade in New York maintained a rally triggered by the US stimulus package, and helped pull less optimistic European markets along behind it.