The Washington man who developed the first case of the novel coronavirus in the U.S. had at least 16 close contacts before he was placed in isolation, health officials said Wednesday. The officials stressed that the risk to the public remains low.

The Wednesday night press conference came two days after the Centers for Disease Control and Prevention announced that a man in his 30s — who recently flew to Seattle from Wuhan, China — was the first confirmed case of the new virus strain in the U.S.

The man is being treated at Providence Regional Medical Center in Everett, outside Seattle, and is in good condition, officials said Wednesday. After interviewing him about what he did when he returned to Washington, officials said they identified 16 people who came in close contact with him before he was put in isolation.

The officials defined close contact as a person who was within 6 feet of the patient for a prolonged period of time.

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Officials began reaching out to those contacts on Tuesday. "All the close contacts will be part of what we call 'active monitoring,'" said Washington state Secretary of Health John Wiesman.

"That means that a public health worker will call the person daily to do a symptom check for them, see if they have a fever, cough, any respiratory issues. And should anyone develop symptoms at any point in time, these people who are under monitoring will be instructed to immediately call a public health worker to report the symptoms, and then we would help facilitate a medical evaluation."

Because officials believe that patients don't become infectious until they begin experiencing symptoms, the close contacts have not been placed in isolation.

Officials emphasized the patient is faring well, and that the risk to the public is low. They added that the patient is the only person in the U.S. who has been tested for the virus.

"Patient continues to rest comfortably, appears in no distress," said Dr. Jay Cook, the chief medical officer at the Providence Regional Medical Center. "I had the opportunity to go by the unit early this morning, the patient was asleep, so I didn't wake him up, but the staff reported that he had a really good night."

The virus is believed to have originated at a food market in Wuhan, a city of 11 million people. But officials said the U.S. patient said he was "just traveling through the area," and did not visit the market or know anyone who was ill.

Officials added the man did not take a direct flight from Wuhan, but they declined to say which airports he flew through en route to Seattle-Tacoma International Airport on January 15.

Washington Governor Jay Inslee said Tuesday night that the man fell ill a day after arriving in the U.S., and sought medical treatment on the same day. He added that the man lived alone and traveled alone.

Dr. Nancy Messonnier, director of the CDC's National Center for Immunization and Respiratory Diseases, told reporters Tuesday that the first U.S. case "is concerning."

"We expect additional cases in the U.S.," she said.