A ninth person has died from the coronavirus in Washington state, the location of all of the deaths in the US to date.

According to officials in King County, the patient was in her 80s and died at home on 26 February. Eight of the deaths are in King County, which has 21 cases, and one death is in Snohomish County, which has six cases.

The King County deaths are concentrated at a nursing home in Kirkland, near Seattle. Earlier on Tuesday, a resident of the nursing home tested positive posthumously. They died last week ahead of the other deaths at the home.

Relatives of LifeCare Centre's residents told CBS News that their elderly loved ones are isolated in their rooms and their temperatures are monitored daily.

There is concern that those not showing symptoms will not be tested or received appropriate care until they become critically ill. “They're being held hostage in a petri dish,” one relative said.

A Homeland Security facility in King County had to be closed because an employee became ill after visiting a family member at the LifeCare Centre.

Acting US Department of Homeland Security Secretary Chad Wolf told Congress' Homeland Security Committee that employees were told to work from home for the next 14 days and to “self-quarantine”.

The Associated Press reports that Mr Wolf praised the employee for not going to work after becoming ill and said the office was being closed “out of an abundance of caution.”

Acting Secretary of Homeland Security Chad Wolf testifies before a House Committee on Homeland Security hearing on the coronavirus and the FY2021 budget (AP Photo/Alex Brandon)

In a press call on Tuesday, Dr Nancy Messonnier of the Centres for Disease Control and Prevention said: “What is happening now in the United States may be the beginning of what is happening abroad.”

Evidence from China, where the outbreak began more than two months ago, indicates that older and sicker people are about twice as likely to become seriously ill as those who are younger and healthier.

Researchers believe the virus may have been circulating undetected for weeks in Washington state, raising fears that there could be hundreds of undiagnosed cases in the area —indeed, the same could be true elsewhere in the US.

In Washington, Congress moved forward with a bipartisan $7.5 billion emergency bill to fund the government's response to the outbreak, however lawmakers on Capitol Hill expressed frustration with the pace at which widespread testing is being rolled out.

Doubts have been raised about claims by the Food & Drug Administration Commissioner that US labs would be able to perform “close to 1 million” coronavirus tests by the end of the week. That statement from Stephen Hahn came during a White House briefing on the coronavirus on Monday evening.

But testing so far has faced delays and missteps, and “I'm hearing from health professionals that's unrealistic,” Democratic Senator Patty Murray of Washington state said at a Senate hearing. CDC test kits delivered to states and cities in January proved faulty.

Politico reports that the 1 million figure far exceeds the number of tests that labs say that they will actually be able to run each day and commercial tests are weeks away from approval. Figures provided by the Association of Public Health Laboratories indicate that under ideal conditions, US public health labs could run up to 10,000 tests per day by the end of the week.

Senator Patty Murray of Washington state, speaks with reporters after meeting with Vice President Mike Pence, the head of President Donald Trump's coronavirus task force, on Capitol Hill (AP Photo/Andrew Harnik) ((AP Photo/Andrew Harnik))

A spokesperson for the FDA says that the figure Mr Hahn quoted includes commercial tests that the agency wants to bring to market by the end of the week.

New regulations issued by the FDA do allow for some labs to create and use their own tests and then seek authorisation for emergency use. Mr Hahn told reporters that this new policy has garnered a response from multiple companies and academics, and the number of tests being performed should rise quickly over the next few weeks.

However, fewer than half of the 100 public health laboratories have successfully verified the CDC diagnostic. It is hoped that all of the labs will be in some stage of verification by the end of the week now that the CDC is distributing more test kits.

“The people across my state are really scared. I´m hearing from people who are sick, who want to get tested and don´t know where to go,” Senator Murray said. “It´s unacceptable that people in my state can´t even get an answer as to whether or not they are infected.”