President Donald Trump has appointed Vice-President Mike Pence to co-ordinate the US government’s response to the coronavirus outbreak.
Both men told a White House news conference that the risk to the American people remained very low.
The announcement came as new cases of the infection caused by the coronavirus which originated in China spread at a rapid pace around the world.
The 60th case in the US is also the first to occur on US soil.
The unidentified person in California had “no relevant travel history or exposure to another known patient” with the virus, said the Centers for Disease Control (CDC).
Addressing the press, Mr Trump expressed confidence that the US would be able to handle coronavirus.
“We’re very, very ready for this,” Mr Trump said, that Mr Pence has “got a certain talent for this”.
Researchers were “rapidly developing” a vaccine.”