Federal officials have launched an investigation into the Seattle nursing at the centre of a major coronavirus outbreak, as the death toll in the US climbed to 11.

As Mike Pence prepared to visit Washington state and tens of thousands of technology firm employees were advised to work from home to try and reduce the spread of the virus, authorities said they would be probing the LifeCare Centre in Kirkland, a suburb of Seattle.

Ten of the US’s eleven fatalities have been in Washington state, and most of them were residents of the care facility. At least 39 cases have been reported in the state and officials believe the virus may have been undetected for weeks.

Seema Verma, the head of the centres for medicare and medicaid services (CMS), part of the department of health and human services, said in a media briefing she was ordering state authorities monitoring care facilities to focus on limiting infections.

The action was being take, she said, to “make sure that we’re doing everything we can as a health care system to contain the spread of the coronavirus”.

Streets of Venice empty due to Coronavirus fears Show all 16 1 /16 Streets of Venice empty due to Coronavirus fears Streets of Venice empty due to Coronavirus fears Gondoliers wait for customers in Venice, Italy, Friday, Feb. 28, 2020. Authorities in Italy decided to re-open schools and museums in some of the areas less hard-hit by the coronavirus outbreak in the country which has the most cases outside of Asia, as Italians on Friday yearned for a return to normal life even amid fears that the outbreak could plunge the country's economy into recession. AP Streets of Venice empty due to Coronavirus fears Gondoliers wait for customers in Venice, Italy, Friday, Feb. 28, 2020. Authorities in Italy decided to re-open schools and museums in some of the areas less hard-hit by the coronavirus outbreak in the country which has the most cases outside of Asia, as Italians on Friday yearned for a return to normal life even amid fears that the outbreak could plunge the country's economy into recession. AP Streets of Venice empty due to Coronavirus fears A man wearing a protective mask walks past the Ponte di Rialto (Rialto Bridge) in Venice, Italy, Friday, Feb. 28, 2020. Authorities in Italy decided to re-open schools and museums in some of the areas less hard-hit by the coronavirus outbreak in the country which has the most cases outside of Asia, as Italians on Friday yearned for a return to normal life even amid fears that the outbreak could plunge the country's economy into recession. AP Streets of Venice empty due to Coronavirus fears A gondolier on the Grand Canal as the sun sets in Venice, Italy, Friday, Feb. 28, 2020. Authorities in Italy decided to re-open schools and museums in some of the areas less hard-hit by the coronavirus outbreak in the country which has the most cases outside of Asia, as Italians on Friday yearned for a return to normal life even amid fears that the outbreak could plunge the country's economy into recession. AP Streets of Venice empty due to Coronavirus fears A local pulls a trolley as she leaves a street food market in Venice, Saturday, Feb. 29, 2020. A U.S. government advisory urging Americans to reconsider travel to Italy due to the spread of a new virus is the "final blow" to the nation's tourism industry, the head of Italy's hotel federation said Saturday. Venice, which was nearing recovery in the Carnival season following a tourist lull after record flooding in November, saw bookings drop immediately after regional officials canceled the final two days of celebrations this week, unprecedented in modern times. AP Streets of Venice empty due to Coronavirus fears Locals wait for a mass at the barely empty San Salvador church in Venice, Sunday, March 1, 2020. A coughing Pope Francis told Italy, pilgrims gathered for the traditional Sunday blessing that he is canceling his participation at a week-long spiritual retreat in the Roman countryside because of a cold. It is the first time in his seven-year papacy that he has missed the spiritual exercises that he initiated early in his pontificate to mark the start of each Lenten season. AP Streets of Venice empty due to Coronavirus fears Tourists wearing protective masks take photographs in Venice, Sunday, March 1, 2020. Italian tourism officials are worrying a new virus could do more damage to their industry than the Sept. 11 terror attacks as the country's confirmed cases surpassed 1,000. AP Streets of Venice empty due to Coronavirus fears Tourists wearing protective masks look at their smartphones as they have a break at the St. Mark's square in Venice, Sunday, March 1, 2020. Italian tourism officials are worrying a new virus could do more damage to their industry than the Sept. 11 terror attacks as the country's confirmed cases surpassed 1,000. AP Streets of Venice empty due to Coronavirus fears A couple stand at the Rialto bridge during a rainy day in Venice, Sunday, March 1, 2020. Italian tourism officials are worrying a new virus could do more damage to their industry than the Sept. 11 terror attacks as the country's confirmed cases surpassed 1,000. AP Streets of Venice empty due to Coronavirus fears An empty canal is seen after the spread of coronavirus has caused a decline in the number of tourists in Venice, Italy, March 1, 2020. REUTERS Streets of Venice empty due to Coronavirus fears An empty canal is seen after the spread of coronavirus has caused a decline in the number of tourists in Venice, Italy, March 1, 2020. Reuters Streets of Venice empty due to Coronavirus fears An empty canal is seen after the spread of coronavirus has caused a decline in the number of tourists in Venice, Italy, March 1, 2020. REUTERS Streets of Venice empty due to Coronavirus fears An empty canal is seen after the spread of coronavirus has caused a decline of tourists in Venice, Italy, March 1, 2020. REUTERS Streets of Venice empty due to Coronavirus fears An empty water bus after the spread of coronavirus has caused a decline in the number of tourists in Venice, Italy, March 1, 2020. REUTERS Streets of Venice empty due to Coronavirus fears Tourists shelter against the rain with umbrellas as they walk in the empty St. Mark's Square during a rainy day in Venice, Sunday, March 1, 2020. Italian tourism officials are worrying a new virus could do more damage to their industry than the Sept. 11 terror attacks. AP Streets of Venice empty due to Coronavirus fears Gondolas are parked on a rainy day in Venice, Sunday, March 1, 2020. Italian tourism officials are worrying a new virus could do more damage to their industry than the Sept. 11 terror attacks. AP

She said the CMS was sending inspector to LifeCare, along with experts from the centres for disease control and prevention.

Last April, Washington state fined LifeCare $67,000 over infection-control deficiencies following two flu outbreaks that affected 17 patients and staff. An unannounced follow-up inspection in June determined that Life Care had corrected the problems, said Ms Verma.

The probe came as tens of thousands of employees from companies such as Amazon, Microsoft, Starbucks and Expedia, were advised to work from home.

England's chief medical officer says UK has moved to 'delay phase' of tackling coronavirus

Amazon, which has its headquarter in Seattle, recommended employees in the area to work from home until the end of the month, after an employee tested positive for the coronavirus on Tuesday.

Also, Facebook said a contractor at its Seattle office was diagnosed with the coronavirus and that it would shut the location until March 9. “A contractor based in our Stadium East office has been diagnosed with the COVID-19,” the company said.

Officials have suggested organisations postpone or cancel activities that involve gatherings of more than ten people.

“We have encouraged people who are responsible for large gatherings to give consideration whether it really makes sense to carry those on right now,” said governor Jay Inslee said. “Right now, we are deferring to the judgment of these organisations.”

On Wednesday night, California declared a state of emergency as officials said an elderly person from Placer County, near Sacramento, had died after testing positive after returning from a San Francisco-to-Mexico cruise.

In the nation’s capital, Donald Trump again played down the threat the virus posed.

He told Fox News the 3.4 per cent mortality rate announced by the World Health Organisation was “false” and suggesting it was under 1 per cent. He said: “This is really my hunch.”