The first case of possible "community spread" of the coronavirus — meaning the origin by which a person was infected is unknown — was detected in the US.

The patient is being treated at UC Davis Medical Center after being transferred from VacaValley hospital in Vacaville after her condition worsened, KGO reported.

A UC Davis internal memo said medical workers requested that the person be tested a week ago, but the CDC declined to test the patient as the person did not meet the required criteria for a test.

The patient had not recently traveled to China nor had any known contact with another person infected with COVID-19.

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The Centers for Disease Control and Prevention has confirmed what may be the first case of community spread of the coronavirus in the US — in which the origin by which a person was infected is unknown.

The CDC said the woman "reportedly did not have relevant travel history or exposure to another known patient with COVID-19."

The patient, who is the 15th confirmed case of the coronavirus in the US, is being treated at UC Davis Medical Center after being treated at VacaValley hospital in Vacaville, California, KGO reported.

"At this time, the patient's exposure is unknown," the CDC said in a statement. "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."

A UC Davis internal memo said that the woman was transferred from another hospital on February 19 but that the CDC declined to test the person, who had not traveled to China or had known contact with another person infected with COVID-19.

"Upon admission, our team asked public health officials if this case could be COVID-19," the memo said. "We requested COVID-19 testing by the CDC since neither Sacramento County nor CDPH is doing testing for coronavirus at the time.

"Since the patient did not fit the existing CDC criteria for COVID-19, a test was not immediately administered. UC Davis Health does not control the testing process," the memo continued.

UC Davis Medical Center said it suspected a viral infection and had implemented "droplet protection orders" and on Sunday, when the person was tested, "airborne precautions."

The hospital said this was not the first coronavirus case it had treated and believed there was "minimal potential exposure." The memo did say that some healthcare workers were told to stay home and monitor their temperature.

Rep. John Garamendi of California, who represents the district where the patient is being treated, tweeted that he was in "close contact" with the CDC and the state regarding the situation.

"We all have the responsibility to protect ourselves and others by washing our hands and carrying out procedures to avoid infecting ourselves and others," he continued. "Please monitor CDC's website and Facebook for further information."

At least 60 cases have been reported in the US: 15 US cases; 43 Americans who were repatriated from the Diamond Princess cruise ship, which was under quarantine in Japan; and three people who were evacuated from Wuhan, China, the origin of the novel coronavirus outbreak.

As of Wednesday, the coronavirus has amassed a death toll of over 2,800 people and infected over 82,000 worldwide, with the vast majority of cases and deaths in China.

Business Insider could not immediately reach UC Davis Medical Center.