US President Donald Trump vowed to sign Wednesday an order partially blocking immigration to the United States as health experts warned that a second US coronavirus wave could be even more destructive.

And the World Health Organization said there was still a long way to go to defeat the virus, with most countries still in the early stages of dealing with the pandemic.

Trump said his action was being taken “to protect American workers” after 22 million people lost their jobs in the United States alone in the devastating economic backlash sparked by unprecedented measures taken to halt the spread of the virus.

With large swathes of businesses hurt in the crisis and employees forced to stay home or work shorter hours, the United Nations warned that the world is facing “a humanitarian catastrophe” with millions on the brink of starvation.

Nations around the world have been scrambling to fight the pandemic — which has killed almost 178,000 people and infected more than 2.5 million worldwide — while desperately seeking ways to limit the colossal damage inflicted on the global economy.

“Make no mistake: we have a long way to go. This virus will be with us for a long time,” WHO director-general Tedros Adhanom Ghebreyesus told a virtual press conference.

Worst-hit region Europe saw its death toll climb to another grim milestone of 110,000, while Italy, the hardest hit country behind the United States, saw its fatalities top 25,000.

Spain reported a slight increase for a second day running in the number of people who succumbed to the disease and parliament is expected Wednesday to extend a strict lockdown.

But Germany, which this week cautiously began allowing shops to reopen, offered another glimpse of hope when it announced trials on human volunteers for a vaccine will start by next week.

The trial, which was only the fourth to have been authorised worldwide, was a “significant step” in making a vaccine “available as soon as possible”, regulator the Paul Ehrlich Institut said.

But with months to go before a viable vaccine can be rolled out, more than half of humanity remains under some form of lockdown.

Singapore extended its confinement for a month to June 1, as the Asian city-state which managed to keep its outbreak in check early on is hit by the onslaught of second wave of infections.

The director of the US Centers for Disease Control also warned Americans to prepare for a more ferocious second wave.

“There’s a possibility that the assault of the virus on our nation next winter will actually be even more difficult than the one we just went through,” Robert Redfield told the Washington Post.

In South Africa, more than 73,000 extra troops were sent out to enforce a shutdown as authorities struggled to keep people indoors — particularly in overcrowded townships.

With businesses shuttered and millions of jobs lost, the world is facing its worst economic downturn since the Great Depression, and the UN’s World Food Programme (WFP) said it would hit the least privileged the hardest.

“I want to stress that we are not only facing a global health pandemic but also a global humanitarian catastrophe,” WFP executive director David Beasley told the UN Security Council Tuesday.

“Millions of civilians living in conflict-scarred nations… face being pushed to the brink of starvation.”

The WFP said the number of people suffering from acute hunger was projected to nearly double to 265 million this year.

Standing in line in Bangkok’s historic quarter for food donations of rice, noodles, milk and curry packets, Chare Kunwong, a 46-year-old masseur said: “If I wait for the government’s aid then I’ll be dead first.”

Among the hardest hit economically were also millions of migrant workers from South Asia and elsewhere who toil in the Middle East to send money back home to their families.

Remittances are expected to plunge by about 20 percent globally this year, the biggest decline in recent history, the World Bank said in a report of the money transfers that are lifelines to millions of families.

The pandemic shutdowns mean even bodies of some migrant workers cannot be sent home, and are instead being buried or cremated in the country where they die — often without any loved ones present.

“Nobody comes anymore, nobody touches, nobody says goodbye,” said Ishwar Kumar, manager of a Hindu cremation ground in Dubai.

Before the pandemic, people would come “to grieve and bring flowers. Now they die alone”.

In the United States, Trump said he would stop the issuing of green cards for 60 days, but exempt temporary workers such as seasonal farm laborers.

“It will help put unemployed Americans first in line for jobs as America reopens,” he said.

“It would be wrong and unjust for Americans to be replaced with immigrant labor flown in from abroad.”

The US — with nearly 45,000 deaths and more than 800,000 coronavirus infections — is the hardest-hit country, and healthcare infrastructure in major hotspots such as New York City has struggled to cope.

Furious over the devastating epidemic, the US state of Missouri sued China’s leadership, seeking damages over what it described as deliberate deception and insufficient action to stop the pandemic.

The first-of-its-kind state lawsuit comes amid calls in Congress to punish China and a campaign by Trump to focus on Beijing’s role as he faces criticism over his own handling of the crisis.

It also sparked an angry rebuke from Beijing over what it described as an “absurd” claim.

Away from the diplomatic barbs, doctors and nurses at the frontlines of the war against the pandemic voiced desperation at the endless fight.

“The same thing every day… is draining,” said Heather Isola, a physician assistant in New York.

But the pandemic has also brought great courage to the fore, particularly among healthcare workers in the worst-hit places.

Sharing their determination as they battle the disese in an intensive care unit in suburban Rome’s Tor Vergata hospital, nurse Alessandro Iacchetti, 58, said his message to the world is: “Never give up.”