The first case of possible "community spread" — in which the origin by which the individual was infected is unknown — was detected in the US.
The patient is being treated in UC Davis Medical Center after being transferred from another hospital in northern California.
A UC Davis internal memo said medical workers requested the individual be tested a week ago, but the CDC declined to test the patient as they did not meet the required criteria for a test.
The patient had not recently travelled to China nor had any known contact with another person infected by COVID-19.
The Centers for Disease Control and Prevention (CDC) confirmed the first case of community spread in the US — in which the origin by which the individual was infected is unknown.
The CDC said that they "reportedly did not have relevant travel history or exposure to another known patient with COVID-19."
The patient, who is the fifteenth confirmed case of the coronavirus in the US, is being treated at the University of California, Davis Medical Center after being treated at another hospital in northern California.
"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 the patient was transferred from another hospital a week ago, but the CDC declined to test the individual, as the patient had not travelled to China nor had known contact with another person infected by COVID-19.
"Upon admission, our team asked public health officials if this case could be COVID-19," the memo read. "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 they suspected a viral infection and had implemented "droplet protection orders" and on Sunday when they were tested, "airborne precautions."
The hospital said that this was not the first patient with coronavirus that they have treated, and they believe there was "minimal potential exposure." The memo did state 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 he is 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 aboard the Diamond Princess cruise ship, which was under quarantine in Japan were repatriated, as well as three individuals who were evacuated from Wuhan, China, the epicenter of the coronavirus outbreak.
As of Wednesday, the coronavirus has amassed a death toll of over 2,800 people, and infected over 82,000 worldwide.
Business Insider could not immediately reach UC Davis Medical Center.