The US’s response to the coronavirus continues to highlight cracks in the nation’s governance, with Donald Trump reversing his position on cruise liners at the same time as the crew of a navy aircraft carrier pleads for help with an onboard outbreak.

The US death toll from the coronavirus has climbed past 3500, eclipsing China’s official count, and there is mounting concern about infection rates in New York, which threaten to swamp the health services.

On Tuesday (local time), Mr Trump warned Americans to brace for a “rough two-week period” ahead as the White House released new projections that there could be 100,000 to 240,000 deaths in the US from the coronavirus pandemic, even if current social distancing guidelines are maintained.

On Wednesday, a leaked memo indicated the captain of the USS Theodore Roosevelt faced a growing outbreak and had wanted to be allowed to isolate the bulk of his roughly 5000 crew onshore to try to save lives.

In a memo to Navy leaders, Captain Brett Crozier said the coronavirus spread was accelerating and removing 90 per cent of his crew from teh carrier was a “necessary risk”. The ship is docked in Guam.

Navy leaders are scrambling to determine how to best respond to the extraordinary request as dozens of crew members have tested positive for the coronavirus.

“We are not at war. Sailors do not need to die,” Captain Crozier said in a memo obtained by The Associated Press.

If we do not act now, we are failing to properly take care of our most trusted asset our sailors.”

US Pacific Fleet commander Admiral John Aquilino said on Tuesday that the Navy was working to get as many sailors as possible to shore, while still maintaining a core crew to monitor the ship’s nuclear reactors and keep it running.

While that crisis was unfolding, Mr Trump urged Florida officials to open an Atlantic Coast port to a Dutch cruise ship stuck at sea with an outbreak onboard.

Weighing in on the fate of Holland America Line’s MS Zaandam during a White House briefing, the US president said he would call Florida governor Ron DeSantis. Mr DeSantis has declared the vessel unwelcome in his state, to prevent its sick passengers from being “dumped” there.

“They’re dying on the ship,” Mr Trump said, adding, “I’m going to do what’s right, not only for us but for humanity.”

The remarks contrast with his response in February to a different cruise ship, the Grand Princess, which he said should remain at sea instead of coming into port in California.

The Zaandam, which had been idling off the Pacific coast of Central America after the cruise line said some passengers had the coronavirus and four had died, was allowed to sail through the Panama Canal into the Caribbean on Sunday.

Nearly two-thirds of the passengers – those who passed a medical screening – were moved onto the Zaandam’s sister ship, the Rotterdam, before the canal transit. Both vessels are headed to Port Everglades in Fort Lauderdale, Florida, officials said.

The Zaandam was carrying nearly 1050 passengers and crew, and the Rotterdam almost 1450. But it remained uncertain who would be permitted to disembark in Florida, where concerns about the spread of coronavirus are mounting.

“We cannot afford to have people who aren’t even Floridians dumped into South Florida using up those valuable resources,” Mr DeSantis told Fox News on Monday, referring to the state’s medical facilities.

He said he preferred to send medical help to the Zaandam.

But in a blog posted the website of Holland America, a unit of world cruise leader Carnival Corp, company president Orlando Ashford urged authorities to show compassion.

“We are dealing with a ‘not my problem’ syndrome,” he said. “The international community, consistently generous and helpful in the face of human suffering, shut itself off to Zaandam.”

In New York, which is considered the epicentre of the virus crisis in the US, governor Andrew Cuomo said his brother, CNN anchor Chris Cuomo, has become infected.

Tweet from @SaltMerchantYT

“There’s a lesson in this,” Governor Cuomo said of his 49-year-old brother, who is now in quarantine.

“He’s an essential worker, a member of the press so he’s been out there. If you go out there, the chance that you get infected is very high.”

There have already been about 1550 coronavirus deaths in New York State, the majority of them in New York City.

A Navy hospital ship with 1000 beds that docked in New York on Monday was expected to begin accepting non-coronavirus patients on Tuesday.

-with AAP