MAPLEWOOD (Minnesota) • US Vice-President Mike Pence has acknowledged that there is a shortfall in the number of coronavirus testing kits required to meet demand, as the number of people catching the new disease hit 233 in the United States.

"We don't have enough tests today to meet what we anticipate the demand (will be) going forward," he said during a visit to a 3M plant in Minnesota on Thursday.

"We are focused very much on a cruise ship just off the California coast today. The Coast Guard delivered a sufficient number of tests for the passengers on that ship."

A batch of diagnostic kits was flown by helicopter on Thursday to the Grand Princess idled off the coast of California and barred from docking in San Francisco after at least 35 people developed flu-like symptoms on board the ship, which has been linked to two other Covid-19 patients. One of the two patients has since died.

Officials said there were 2,383 passengers and 1,100 crew on board the ship.

The Grand Princess belongs to Princess Cruises, the same company which operated the Diamond Princess - the coronavirus-stricken ship held off Japan last month from which more than 700 people tested positive and six died.

"As more Americans take an interest in this or have concerns about this, we want to make sure they have access to the coronavirus test as well, and we have made real progress on that in the last several days," said Mr Pence.

US health officials say they expect to be able to get enough privately manufactured coronavirus tests - around one million - to public laboratories this week with the capacity to test about 400,000 people.

US Centres for Disease Control and Prevention (CDC) official Anne Schuchat said her agency would also supply testing kits by the end of the week that could test around 75,000 people.

US Health and Human Services Secretary Alex Azar told reporters following a briefing with lawmakers: "Right now, it is a challenge if you are a doctor wanting to get somebody tested."

At least 57 new coronavirus cases were confirmed nationwide on Thursday as the virus struck for the first time in Colorado, Maryland, Tennessee and Texas, as well as the city of San Francisco.

The death toll from the respiratory illness rose to 14 in the US, with the latest fatalities recorded in King County, Washington, where several people have died in an outbreak at a nursing facility in the Seattle suburb of Kirkland.

Twenty new cases were confirmed in King County, which is home to Seattle and has been the site so far of the greatest concentration of coronavirus cases in the country, bringing the total in the county to 51, with 12 deaths.

One death has been recorded in California. At least several people suffering from the virus are said to be gravely ill.

The US Senate on Thursday passed a US$8.3 billion (S$11.4 billion) Bill to combat the outbreak by 96-1, a day after the House of Re-presentatives overwhelmingly approved it.

More than US$3 billion of that money is intended for research and development into vaccines, test kits and treatments.

"The American people are looking for leadership, they want assurance their government is up to the task of protecting their health and safety," said Democratic Senator Patrick Leahy.

The amount is significantly above the US$2.5 billion President Donald Trump had initially requested, but he later said he was happy to accept more.

Mr Pence said Mr Trump would sign the Bill into law yesterday.

Thirteen of the 14 US fatalities from the outbreak have been in the north-west state of Washington, leading to an emergency declaration by the state and proactive measures in the community where technology plays a major role in the economy.

Technology firms in Seattle were telling employees this week to take advantage of technology to work remotely in an effort to contain the outbreak.

Online retail and cloud computing colossus Amazon, which has transformed the north-western US city with its urban campus, has given its more than 50,000 employees in the region the green light to work remotely.

Facebook and Google, which have been steadily expanding operations in Seattle, are also encouraging workers in Washington state to stay away from the office to reduce risks amid a global outbreak which has killed more than 3,000 people and led to the closing of schools and factories in some countries.

Microsoft, with its headquarters in Redmond, a short distance from Seattle, put out word to employees this week that, if possible, they should work from their residence for the next few weeks.

Some schools in the state have also decided to close for a few weeks and hold classes online.

US officials continue to stress that the overall risk to the public remains low, and are urging people not to panic or buy masks - which could create a shortage for those who require them.

The scientific literature so far shows that elderly people and those with underlying conditions are most at risk of a serious illness, and the majority of US deaths so far have occurred in the Seattle-area nursing home.

But the largest nursing union in the US denounced on Thursday the "disturbing" lack of preparation at many hospitals.

Nurses are working without the necessary personal protective equipment, and lack education and training for handling the disease, said National Nurses United director Bonnie Castillo.

"As of today, more than 80 of our nurse members have been in quarantine," she said at a news conference in California held by the union, which claims 150,000 members.

"It is not a successful strategy to leave nurses and other health workers unprotected."

REUTERS, AGENCE FRANCE-PRESSE