A confirmed coronavirus patient in California had no travel history in China and no known exposure to the virus.
According to health officials, this is the first potential case of "community spread" in the US.
"Community spread' reflects the fact that the virus is out there in the community spreading from person to person.
How the Solano County, California patient contracted the COVID-19 virus remains a mystery.
One health official said this requires a transition "from trying to contain the disease to more of a mitigation approach."
The California patient is now in serious condition, according to Business Insider.