Authorities across the US reported 308 cases of coronavirus and 17 deaths as of Friday, with Florida reporting the first deaths on the East Coast. The number of infections does not count the 21 people who have tested positive aboard a cruise ship off California, the Grand Princess.

Florida officials on Friday night said there had been two deaths in the state related to the coronavirus. Both of the people who died had travelled internationally, they said.

Hawaii reported its first confirmed infection, a person who had been on the Grand Princess.

The West Coast has borne the brunt of the toll in the US. Washington state has recorded the most coronavirus cases, more than 80, and the highest number of deaths, 14. Most of the fatal cases emerged from a Seattle-area nursing home. Officials in King County, Washington, said 15 residents of the facility, Life Care Center, had been taken to hospitals over the past 24 hours.

Two residents of other Seattle-area complexes that largely serve elderly people have now also been hospitalised and tested positive, officials said, identifying them as Issaquah Nursing & Rehabilitation Center and Ida Culver House Ravenna.

California has treated 70 people for the virus, one of whom has died, and new cases continue to emerge at a worrying rate. An employee of the FBI’s San Francisco division tested positive, the first confirmed case at the bureau.

And Starbucks on Friday night reported that one of its employees in downtown Seattle had tested positive. The company said the store has been closed for cleaning.

Also in the Seattle area, two Microsoft employees were being treated for the coronavirus, a company spokesman said. Microsoft did not close its campus, but it had already advised employees to work from home if possible.

Two residents of other Seattle-area complexes that largely serve older people have now also been hospitalised and tested positive, officials said, identifying them as Issaquah Nursing & Rehabilitation Center and Ida Culver House Ravenna.

The chief federal judge in Seattle ordered the cancellation of all in-person federal court hearings in Western Washington State. And Hawaii reported its first confirmed infection, a person who had been on the Grand Princess.

Seattle University, with about 7,300 students, also said it would move to online classes for the rest of the winter quarter, and Northeastern University in Boston will do the same for students on its Seattle campus.

But New York City’s public schools will probably stay open even if the new coronavirus becomes more widespread. Richard A. Carranza, the schools chancellor, said this week that he considered long-term closings an “extreme” measure and a “last resort”. New York City has the largest public school system in the US.