https://www.foxnews.com/health/coronavirus-began-spreading-california-december
Coronavirus began spreading in California as early as December, official says 6park.com
In California, the novel coronavirus may
 have begun spreading — albeit quietly — since December, at least a 
month before the first U.S. case was confirmed in Washington state, a 
local official in the state recently said.
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“The
 virus was freewheeling in our community and probably has been here for 
quite some time,” Dr. Jeff Smith, a physician and chief executive of 
Santa Clara County government, reportedly said during a recent briefing 
with county leaders, the Los Angeles Times reported.
Smith,
 citing data from the Centers for Disease Control and Prevention (CDC), 
local health departments and beyond, later told the paper in an 
interview that the virus was possibly circulating in the Bay Area “a lot
 longer than we first believed,” and possibly “since back in December.”