The number of confirmed coronavirus cases passed 1,000 in the US on Tuesday, with at least 31 people dead and federal officials reportedly scrambling to respond to the outbreak.

With experts warning that the virus's spread across the country is now inevitable, the nation’s top health officials said citizens need to begin preparing to face significant impacts to their daily lives.

Dr Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said in a statement: "We would like the country to realise that as a nation, we can't be doing the kinds of things we were doing a few months ago. It doesn't matter if you're in a state that has no cases or one case.”

The White House has been accused of sending mixed messages over the virus, at times claiming tests would be free and made available to anyone who wants one, later walking back those comments and acknowledging there would not be enough tests to meet demand in the coming weeks.

Donald Trump has previously said he was not happy about the rising number of cases in the US, and celebrated claims that the rate of cases would soon go down about two weeks ago.

In a statement on 26 February, the president said: “And again, when you have 15 people, and the 15 within a couple of days is going to be down to close to zero, that’s a pretty good job we’ve done.”

Alarming clusters of the coronavirus swelled on both coasts of the US on Tuesday, with 70 cases now tied to a biotech conference in Boston and infections turning up at 10 nursing homes in the hard-hit Seattle area.

Presidential candidates Bernie Sanders and Joe Biden abruptly cancelled rallies because of worries about the virus, and New York’s governor announced he is sending the National Guard to scrub public places and deliver food in a New York City suburb that is at the centre of the nation’s biggest known cluster of infections.

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On Wednesday, Washington Governor Jay Inslee will announce a ban on gatherings and events of more than 250 people in the Seattle metro area to try to stop the spread of the outbreak, said a person involved in the planning of the decision. The ban would apply to sporting events like Seattle Mariners baseball and Seattle Sounders football games.

The order would not prohibit the operation of workplaces and is not expected to include school closures, said the person, who spoke on condition of anonymity because they weren’t authorised to discuss the matter publicly.

Santa Clara County in California, home to San Jose and Silicon Valley, on Monday announced a ban on all gatherings of 1,000 people or more.

At least 24 people have died in Washington from Covid-19, most in the Seattle metro area. Nineteen of the deaths are linked to one suburban Seattle nursing home and authorities in King County said the virus has spread to at least 10 long-term care facilities.