Cruise ship must wait off California coast to await Covid-19 tests

US officials have ordered a cruise ship to hold off the California coast to await testing of those aboard for Covid-19, after a passenger on an earlier voyage died and at least one other became infected.

A Coast Guard helicopter was expected to deliver test kits to the Grand Princess once it reached the waters off San Francisco later in the day.

Princess Cruises did not immediately disclose how many people were aboard the vessel, which has a capacity of 3,650 passengers and crew, but said fewer than 100 had been identified for testing.

"The ship will not come on shore until we appropriately assess the passengers," California's governor Gavin Newsom said.

It was the US's first coronavirus death outside of Washington state and brought the US death toll to 11, with most of the victims from a suburban Seattle nursing home.

Another previous passenger has also been taken to hospital.

The cruise line said that no cases of the virus had been confirmed among those still on the ship but that some passengers had experienced flu-like symptoms.

The decision to hold the ship offshore came as federal health authorities announced an investigation of the Life Care nursing home in Kirkland to determine whether it followed guidelines for preventing infections.

Last April, the state fined Life Care 67,000 US dollars over infection-control deficiencies following two flu outbreaks that affected 17 patients and staff.

At least 39 Covid-19 cases have been reported in the Seattle area, where researchers say the virus may have been circulating undetected for weeks.