More than 200,000 people so far have been reported to have the coronavirus that causes COVID-19. The first 100,000 were reported over more than three months; the rest got it in just 12 days.
Secretary of State Mike Pompeo said in a tweet that he is working with his Mexican counterpart "on travel restrictions that balance protecting our citizens from further transmission of #COVID19."
The three passengers and one crew member were aboard the Ruby Princess, which arrived from New Zealand. The ship was carrying 2,700 passengers and 1,100 crew members.
"We're scared of coronavirus and we don't know what God has written for us," says an aid worker. "The precautions being taken here are very little and very weak."
The directive is the widest-ranging so far of any state grappling with the growing COVID-19 epidemic. Gov. Gavin Newsom says he is confident that Californians will comply.
NPR's Rachel Martin talks to Maria Van Kerkhove, an emerging diseases expert at the World Health Organization, about the latest information on the spread of the coronavirus worldwide.
Humans are adaptable, even in pandemic times. As the coronavirus spreads, ordinary citizens in several U.S. cities hit early say they are shifting daily routines to survive and thrive.
Palace officials said despite the diagnosis, the ruler's health is "not worrying at all." As of Thursday, only nine others in the tiny Mediterranean country had confirmed cases of the disease.
The ship, which has reported no cases of coronavirus, has been repeatedly denied port. Now, Hawaii also won't accept the Norwegian Jewel or another ship, the Maasdam, and passengers are worried.