Officials in California have confirmed the second case of coronavirus of unknown origin, indicating the virus appears to be spreading in the state.

A day after officials in the north of California revealed what was believed to be the first case of the disease spreading to a person who did not travel internationally or come into close contact with someone infected, authorities in Santa Clara said a second case had been reported.

Santa Clara County public health department spokesman Maury Kendall said the person was isolated at home.

The New York Times said the finding suggested “coronavirus may already circulating locally in California, passing from person to person”.

It said the case involving a person who had no known risk factors was Solano County, between San Francisco and Sacramento. The new infection is in Santa Clara County, south of San Francisco and which includes the city of San Jose.

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A day earlier, state health officials had pegged the number of people in California with the virus at 33.

Residents of the community where the woman first went to the hospital, in Vacaville, are at the epicentre of what officials are calling a turning point in the spread of the highly contagious coronavirus.

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As infectious disease experts fanned out in Vacaville, some residents in the city of 100,000 stocked up on supplies amid fears things could get worse despite official reassurances, while others took the news in stride.

Vacaville lies between San Francisco and Sacramento in Solano County, in the agricultural central valley and near California’s famous wine region.

It is about 10 miles from Travis Air Force Base, which has been used as a virus quarantine location.

Public health officials said they can find no connection between the infected woman and passengers on the Diamond Princess cruise ship who were evacuated to the base when the ship was docked in Japan.