A California resident whose infection with the novel coronavirus was not detected for several days may be the first case of "community spread" of the virus in the U.S.

The patient, whose illness was confirmed Wednesday, reportedly had not recently traveled to a high-risk area or been in contact with an infected person, and the source of their infection is unknown, the Centers for Disease Control and Prevention said.

"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," the CDC said in a statement. "It's also possible, however, that the patient may have been exposed to a returned traveler who was infected."

The new patient is a Solano County resident and is being treated in Sacramento County, the Los Angeles Times reported . The patient was brought to UC Davis Medical Center from another hospital on a ventilator on Feb. 19. But the CDC did not test the patient for the novel coronavirus, which causes the illness COVID-19, until Feb. 23, the hospital's interim CEO Brad Simmons and UC Davis Health CEO David Lubarsky said in a letter to employees Wednesday.

Photos: The Epicenter of Coronavirus View All 28 Images

"Since the patient did not fit the existing CDC criteria for COVID-19, a test was not immediately administered," they said, noting the person is "possibly the first patient to have received the infection from exposure in the community."

The hospital has been taking precautions since the patient arrived because of their "suspected viral infection," the letter said. Health officials have begun tracking the patient's recent contacts, The Associated Press reported .

The coronavirus has been spreading in other countries – including Japan and Italy – and officials have been closely monitoring for community spread in the U.S. The CDC warned earlier this week that it was a question of when, not if , the virus would spread in U.S. communities.

"The trajectory of what we're looking at … is very uncertain," Dr. Anne Schuchat, the CDC's principal deputy director, said during a press briefing at the White House Wednesday.

As of Wednesday, there were 14 other confirmed coronavirus cases in the U.S. among people who had recently traveled or been exposed to someone who had traveled, according to the CDC. There were an additional 42 cases among people repatriated from a cruise ship that had been quarantined in Japan, and three among people who were evacuated from Wuhan, the Chinese city at the center of the outbreak.

Globally, the virus has infected more than 82,000 people and killed more than 2,800, mostly in mainland China, since it was detected in December.

The outbreak has prompted measures such as airport screenings and mandatory 14-day quarantines for the hundreds of Americans who have been evacuated from China. Earlier this week, the Trump administration requested $2.5 billion in federal funding to fight the virus, though Democrats in Congress say much more will be needed.