WASHINGTON - The United States on Saturday (Feb 29) moved to limit travel to coronavirus-hit countries, announcing expanded travel restrictions on Iran and raising warnings against travel to regions of South Korea and Italy, as a man in the state of Washington became the first in America to die after contracting the virus.

The patient was a medically high-risk man in his 50s with underlying health conditions and no history of travel or contact with a known coronavirus case, said the Public Health Department of King County, Seattle. US President Donald Trump earlier said the patient was a woman at a press briefing.

Washington has declared a state of emergency, and Governor Jay Inslee said officials were considering cancelling sporting events, closing schools and taking any other steps needed to slow the spread of the virus.

The respiratory illness has started spreading within communities in America. Three other cases have been confirmed in recent days in California, Washington and Oregon with no known contact with infected patients or travel to places with the virus.

The US now has at least 68 confirmed cases, including 47 people who were repatriated from Wuhan, China and the Diamond Princess cruise ship.

More cases will come but the risk to Americans remains low, said Mr Trump and other top health officials as they urged the public to remain calm and go about their daily lives.

"Additional cases in the US are likely, but healthy individuals should be able to fully recover," said Mr Trump.

"Americans, independent of where they live in this nation, are at low risk," said CDC director Robert Redfield at the press conference. He added: "I encourage Americans to go about their lives. That includes travel to California, Oregon, and the state of Washington."

Vice-President Mike Pence, who was appointed to coordinate the country's response to the outbreak, said that America had 43 million masks available today - enough to protect patients and healthcare workers - with contracts to produce another 35 million more masks a month.

"The average American does not need to go out and buy a mask," he said amid reports of panic buying of toilet paper, bottled water and hand sanitizer in Hawaii, which imports much of its food and goods.

US Surgeon General Jerome Adams also urged Americans not to buy masks unnecessarily, writing on Twitter on Saturday: "They are not effective in preventing the general public from catching the coronavirus, but if healthcare providers can't get them to care for sick patients, it puts them and our communities at risk."

The White House credits the low number of cases in America with its early action to temporarily ban foreign nationals who have recently visited China from entering the country.

On Saturday, Mr Pence said that existing travel restrictions on Iran would be expanded to include any foreign national who has visited Iran in the last 14 days.

The State Department will also advise Americans not to travel to specific regions in Italy and South Korea most affected by the coronavirus, its highest level of travel advisory.

In addition, the US would work with Italy and South Korea to conduct medical screenings there of any individuals coming into the country, said Mr Pence.

The White House will also hold more briefings to keep the public informed of the situation, said Mr Trump. He added that he would meet pharmaceutical companies on Monday about the quick development of a coronavirus vaccine.

Meanwhile, the Food and Drug Administration on Saturday authorised more laboratories across the country to develop their own coronavirus identification tests, cutting red tape to allow many more patients to get tested and get results within hours instead of in a day or two.

The Centres for Disease Control and Prevention also expanded its criteria for patients to get tested.

"The initial Covid-19 cases in the US were linked to travel to China because travelers from China were the only ones we were testing. We could very well be finding new cases now because we've finally expanded testing criteria," said Johns Hopkins Centre for Health Security epidemiologist Jennifer Nuzzo on Twitter.