CNN  — 

After a US patient contracted novel coronavirus and left medical authorities no clues as to where it came from, the Centers for Disease Control and Prevention has begun sending out new testing guidance to health care workers, the top CDC official said Thursday.

A patient in California who has cornonavirus didn’t travel anywhere known to have the virus, the CDC announced Wednesday night. And the patient wasn’t exposed to anyone known to be infected.

The patient is in serious condition, Rep. John Garamendi, who represents the district in California where the patient is from, told CNN’s “OutFront with Erin Burnett.

“Whether this person can actually talk or not is of question. She’s been intubated, and so may not be in a position to discuss it,” he said.

Earlier in the outbreak, CDC guidance to doctors in the United States was that a patient had to have a travel history to China or be a close contact of someone who had been there before being tested, CDC Director Dr. Robert Redfield said.

The new patient who prompted the guidance change was transferred from another Northern California hospital last week.

According to a letter from UC Davis Health, the patient “did not fit the existing CDC criteria for Covid-19, a test was not immediately administered.” After doctors persisted in their request for the test, on Sunday, CDC w