The World Health Organization has said it is seeing a "very large acceleration" in coronavirus infections in the United States which had the potential of becoming the new epicentre.
Over the past 24 hours, 85% of new cases were from Europe and the United States, WHO spokeswoman Margaret Harris told reporters. Of those, 40% were from the United States.
Asked whether the United States could become the new epicentre, Ms Harris said: "We are now seeing a very large acceleration in cases in the US So it does have that potential.
"...They (the United States) have a very large outbreak and an outbreak that is increasing in intensity," she added.
Overall, the global outbreak was accelerating very rapidly and she expected large increases in case numbers and deaths from the 334,981 cases and 14,510 deaths reported
However, US President Donald Trump has said he will soon call for lifting the lockdown in some parts of the country.
Mr Trump, who faces re-election in November and is keen to avoid extended economic damage, told reporters he would be "opening up our country to business because our country was meant to be open".
During a live town hall broadcast on Fox News Channel and later at a briefing with reporters at the White House, he said he would like to have businesses opening their doors again by Easter, which will be celebrated on 12 April.
"I would love to have the country opened up and just raring to go by Easter," he said on Fox.
The president said the country did not take drastic measures to fight car crashes and flu deaths similar to those it is taking for the coronavirus. He said Americans could continue practicing social-distancing measures, which health experts say are crucial to prevent infection, while also going back to work.
The relaxation could be announced early next week when a 15-day period recommending tight restrictions on social distancing expires, he said, stressing that governors would make final decisions in their own states.
Health officials and state governors dealing with the worst outbreaks have said they expect restrictions will have to continue for some time and New York's mayor called for a nationwide lockdown.
As the number of deaths in the United States from Covid-19 soared to 560, with almost 44,000 declared cases, New York has found itself the US centre of the global pandemic.
Millions of residents have been ordered to stay home and non-essential businesses and schools closed.
New York City has now seen more than 12,000 confirmed cases and almost 100 deaths in the outbreak, which first appeared in the US in Washington state.
Mayor Bill de Blasio warned New York was just at "the beginning" of dealing with the pandemic as soldiers from the National Guard began converting a convention centre into a facility with hospital beds.
"It's going to be bad this week, it's going to be worse the following week," he said.
New York Governor Andrew Cuomo warned that the worst of the coronavirus outbreak would hit his state faster and harder than previously thought, adding that easing the limits too early would cost lives.
"If you ask the American people to choose between public health and the economy, then it's no contest. No American is going to say accelerate the economy at the cost of human life," he said at a convention center in Manhattan that is being converted into a 1,000-bed temporary hospital.
The state of New York is the worst hit by the outbreak, which has infected more than 43,000 people in the United States and killed at least 620. The death toll in New York from the Covid-19 respiratory illness caused by coronavirus has reached 157.
The expected need for hospital beds in New York at the peak of the outbreak has jumped to 140,000, Cuomo said, compared with 110,000 projected recently. Only 53,000 beds are now available.
The rate of infection is now doubling every three days in New York and the worst of the outbreak, known as the apex, could arrive in 14 to 21 days, putting huge pressure on health services, Cuomo said.
In California, the first known death of a child due to the novel coronavirus in the United States was reported Tuesday, despite the disease not typically proving severe for juveniles.
The death of a "youth under the age of 18" from Lancaster, just north of Los Angeles, was confirmed in a statement by county health officials.
"Covid-19 does not discriminate by age, race or income level," said Los Angeles County public health director Barbara Ferrer,.
No further information was given, including the victim's age or sex, or whether they had other health conditions.
Multiple studies have found Covid-19 disproportionately affects older patients and those with underlying conditions.
A recent Centers for Disease Control and Prevention (CDC) report found juveniles "appear to have milder COVID-19 illness," with no intensive care admissions or deaths in the US as of 16 March.
Only two known cases of minors dying from the disease in China have been recorded. In one case, an infant had a pre-existing intestinal condition.
"The risk for serious disease and death in COVID-19 cases among persons in the United States increases with age," the CDC report added.
California has been one of the worst-hit US states during the pandemic.
Los Angeles County, which is home to 10 million residents, has confirmed 662 cases of coronavirus, with at least 11 deaths.
Around 80% of cases of Covid-19 will be a mild to moderate illness, close to 14% have severe disease and around 6% are critical.
Generally, a person needs to be 15 minutes or more in the vicinity of an infected person, within 1-2 metres, to be considered at-risk or a close contact.
In Congress, efforts to advance a nearly two-trillion-dollar rescue of the economy failed for a second straight day after Democrats said the Republican proposal insufficiently protected workers.
Mr Trump said he wanted to get restrictions on movement lifted where possible, so that people can get back to work. He acknowledged that medical advisors focused more on public health than the economy may not agree with his decision.
"The doctors, if it were up to them, they may say 'let's keep it shut down, let's shut down the entire world'," he said.
"We can't do that and you can't do that with the country especially the number one economy anywhere in the world by far."
Meanwhile Mr Trump, who has been accused of racism in labelling the coronavirus pandemic the "Chinese virus," said yesterday that Asian-Americans were not responsible for spreading the disease and needed to be protected.
Mr Trump tweeted: "It is very important that we totally protect our Asian American community in the United States, and all around the world.
"They are amazing people, and the spreading of the Virus....is NOT their fault in any way, shape, or form. They are working closely with us to get rid of it. WE WILL PREVAIL TOGETHER!"
Mr Trump repeated his remarks at a news conference with his coronavirus task force. Asked what prompted them, he replied: "It seems that there could be a little bit of nasty language toward the Asian-Americans in our country and I don't like that at all.
"So I just wanted to make that point, because they're blaming China, and they are making statements to great American citizens that happened to be of Asian heritage, and I'm not gonna let that happen."
It is very important that we totally protect our Asian American community in the United States, and all around the world. They are amazing people, and the spreading of the Virus....— Donald J. Trump (@realDonaldTrump) March 23, 2020
Mr Trump also said antimalarial drugs that are under investigation to treat the new coronavirus could be a "gift from God", despite scientists warning against the dangers of overhyping unproven medicines.
Mr Trump announced last week his administration was working to dramatically expand access to hydroxychloroquine and chloroquine, a related compound, following promising early studies in France and China that found the drugs helped patients suffering from the Covid-19 illness.
Many scientists including Anthony Fauci, the United States' leading infectious disease expert, have urged the public to remain cautious until larger clinical trials validate the smaller studies.
But Mr Trump demonstrated no such restraint at a White House press briefing.
"The hydroxychloroquine and the Z-Pak, I think as a combination probably is looking very, very good," he said.
"There's a real chance that it could have a tremendous impact, it would be a gift from God, if that worked it would be a big game changer," he added, quoting the example of a patient who was ill but recovered after taking the drug.
Broadcaster NBC reported, however, that a woman in Arizona, who heard Mr Trump talk about chloroquine, ended up in hospital and her husband died after they took a form of chloroquine she had used to treat her koi fish.
"I saw it sitting on the back shelf and thought, 'Hey, isn't that the stuff they're talking about on TV?'" NBC quoted the unnamed woman as saying.