The United States' death toll from the new virus climbed to 11 on Wednesday, after California reported the first fatality relating to the disease and announced a state of emergency.
Officials in California's Placer County said an elderly person who tested positive after returning from a San Francisco-to-Mexico cruise had died.
Speaking at a news briefing on Wednesday, California Governor Gavin Newsom declared a statewide emergency as more cases appeared in the south - not just the north of California - as had been case.
"The number of cases in the state of California is 53. And I want to just reinforce that. It's 53," said Governor Newsom. "I've read a lot, seen a lot, been a lot of media reports about the number of people that have tested positive in the state of California. That number as of today is 53."
Secretary of Health & Human Services Agency in California Mark Ghaly reassured citizens that it remains uncommon for those infected with the virus to present severe symptoms, but continued work into pandemic planning is underway as "we anticipate more cases to emerge".
"We continue to work on our pandemic plan for the state, modelling, exactly what we expect to see in the days, weeks and months to come and preparing for those scenarios," said Ghaly.
Director of California Department of Public Health Sonia Angell urged citizens to "pay attention" to health notices that will update on risks to communities.
Shortly before the California death was announced, Princess Cruise Lines notified passengers of its Grand Princess that federal health officials are investigating a "small cluster” of coronavirus cases connected to the ship's mid-February voyage. It asked current passengers to stay in their cabins until they were cleared by medical staff and said those who had been on the previous voyage should contact their doctor if they develop fever or other symptoms.
The Grand Princess is at sea off Mexico and will return early to San Francisco, where CDC (Centers for Disease Control and Prevention) and company officials will meet to determine the course of action, the cruise line said.