“There has already been human-to-human transmission and infection of medical workers," Li Bin, deputy director of the National Health Commission, said at a news conference Wednesday with health experts. “Evidence has shown that the disease has been transmitted through the respiratory tract and there is the possibility of viral mutation."
On Tuesday, the U.S. reported its first case of a new and potentially deadly virus circulating in China, saying a Washington state resident who returned last week from the outbreak's epicenter was hospitalized near Seattle.
The man, identified only as a Snohomish County resident is in his 30s, was in good condition and wasn't considered a threat to medical staff or the public, health officials said.
U.S. health officials stressed that they believe the virus' overall risk to the American public remained low.
In response to the spreading virus, authorities have instituted precautionary health screenings for passengers flying to the U.S. from Wuhan, China, where the outbreak began.
The screenings began over the weekend at San Francisco International Airport, as well as at Los Angeles International Airport and New York City's John F. Kennedy and LaGuardia airports. Checks will expand to Chicago’s O’Hare and Atlanta’s Hartsfield-Jackson airports this week.
The patient in Washington state entered the U.S. through a flight originating in Wuhan, before the airport checks began, the CDC said. Of the 1,200 airport screenings that were conducted as of Tuesday morning, no passenger was determined to have the coronavirus, said Dr. Nancy Messonnier, director of the CDC's National Center for Immunization and Respiratory Diseases.
Other airports around the world had also stepped up monitoring, checking passengers from China for signs of illness in hopes of containing the virus during the busy Lunar New Year travel season.
The hospitalized U.S. resident had no symptoms when he arrived at the Seattle-Tacoma airport last Wednesday, but he started feeling ill on Thursday and went to a doctor on Sunday with a fever and a cough, officials said. Lab testing on Monday confirmed he had the virus.
"The gentleman right now is very healthy," said Dr. Nancy Messonnier of the CDC.
The hospital, Providence Regional Medical Center in Everett, said in a statement that it expected the man would be monitored there at least until Thursday.
CDC officials said they sent a team to Washington to try to track down people who might have come in contact with the man. The hospital also said it was contacting "the small number of staff and patients" who may have been with the man at a clinic.
The man is originally from central China, lives alone in the U.S. and made the trip solo, officials said. There were relatively few people who came in contact with him since he got back, health officials said.
Last month, doctors began seeing the new virus in people who got sick after spending time at a food market in Wuhan. More than 275 cases of the newly identified virus have been confirmed in China, most of them in Wuhan, according to the World Health Organization.
Officials have said it probably spread from animals to people, but this week Chinese officials said they've concluded it also can spread from person to person.
Health authorities this month identified the germ behind the outbreak as a new type of coronavirus. Coronaviruses are a large family of viruses, some of which cause the common cold; others found in bats, camels and other animals have evolved into more severe illnesses.
SARS, or severe acute respiratory syndrome, belongs to the coronavirus family, but Chinese state media say the illness in Wuhan is different from coronaviruses that have been identified in the past. Earlier laboratory tests ruled out SARS and MERS — Middle East respiratory syndrome — as well as influenza, bird flu, adenovirus and other common lung-infecting germs.
The new virus so far does not appear to be as deadly as SARS and MERS, but viruses can sometimes mutate to become more dangerous.
University of Washington coronavirus researcher David Veesler said the public "should not be panicking right now."
The response has been "very efficient," Veesler said. "In a couple of weeks, China was able to identify the virus, isolate it, sequence it and share that information."
Veesler added: "We don't have enough data to judge how severe the disease is."