Four Australians are currently on board the Grand Princess cruise ship currently being held off the coast of California, according to the Department of Foreign Affairs and Trade.
"The Australian Consulate General in San Francisco stands ready to offer consular assistance, in accordance with the Consular Services Charter, to any Australian citizen aboard the vessel, should they request it," a DFAT spokesperson told SBS News.
California declared a state of emergency over the novel coronavirus on Wednesday as the cruise ship was held off the coast over fears of a new outbreak.
Separately, the federal government said it was going to buy 500 million respirators to stockpile for use by healthcare professionals.
The measures came as the death toll in the United States hit 11, including the first fatality in California, and lawmakers in Congress agreed to provide more than US$8 billion to fight the rapidly spreading disease.
California Governor Gavin Newsom announced the emergency measures as he reported the death of an elderly person who had taken a cruise to Mexico.
"The State of California is deploying every level of government to help identify cases and slow the spread of this coronavirus," Mr Newsom told reporters.
The emergency proclamation would help the state prepare "in the event it spreads more broadly," he said.
California Governor Gavin Newsom has ordered some bars to close. Source: AP
Thousands travelling aboard the Grand Princess - the same cruise ship on which California's first victim was thought to have contracted the virus - were held offshore Wednesday night, Pacific time.
The ship cut short its current voyage back from Hawaii after passengers and crew members developed symptoms. But its planned return to San Francisco was held up in order to carry out testing on board for those potentially infected.
"We're holding that ship, which (has) thousands of passengers as well, off the coast, and we'll be conducting those tests," Mr Newsom told a press conference.
Eleven passengers and 10 crew members were potentially infected with the virus, Mr Newsom said.
Some 62 guests who remained on board from the earlier Mexico voyage were being restricted to their cabins for testing, the Princess Cruises company said in a statement to AFP.
"In an abundance of caution, these guests and other potential close crew contacts have been asked to remain in their staterooms until screened by our onboard medical team," it said.
In total, some 2,500 passengers plus crew - typically up to 1,150 - were on board for its Mexico voyage, said Mr Newsom.
The Grand Princess belongs to Princess Cruises, the same company which operated the coronavirus-stricken ship held off Japan last month on which more than 700 people on board tested positive.
with additional reporting from AFP