This suggests the virus could be spreading locally, person-to-person, the CDC said.
"The Centers for Disease Control and Prevention (CDC) has confirmed an infection with the virus that causes COVID-19 in California in a person who reportedly did not have relevant travel history or exposure to another known patient with COVID-19," the CDC said in a press release.
The patient is a resident of Solano County and receiving medical treatment in Sacramento County, according to the California Department of Public Health.
Solano County is home to Travis Air Force Base, where Americans returning from overseas have been quarantined for novel coronavirus screening.
UC Davis Health officials say the patient was transferred to their facility from another Northern California hospital on Feb. 19. They say when the patient arrived, they had already been intubated, were on a ventilator, and were given droplet protection orders because of an undiagnosed and suspected viral condition.
According to UC Davis, their team requested COVID-19 testing by the CDC, however, since the patient did not fit the existing CDC criteria for the virus, the test was not immediately administered.
On Sunday, the CDC ordered COVID-19 testing of the patient and the patient was put airborne precautions because of concerns about their condition.
On Wednesday, the CDC confirmed the patient's test was positive.
UC Davis says out of an abundance of caution, it has asked a small number of employees to stay home and monitor their temperature.
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It is unknown how the patient contracted the virus. If it was contracted in the United States, it would be the country's first case of it spreading here, as opposed to being exposed overseas.
"At this time, the patient's exposure is unknown. It's possible this could be an instance of community spread of COVID-19, which would be the first time this has happened in the United States. Community spread means spread of an illness for which the source of infection is unknown. It's also possible, however, that the patient may have been exposed to a returned traveler who was infected," the CDC explained in their statement.
The case was caught by the public health system in Northern California.
The CDC says the federal government is working with the state of California to "contain the spread and mitigate the impact of this virus."
Stay with ABC7 News for the latest details on this developing story.
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