A patient in Chicago became the second confirmed case of 2019 novel coronavirus in the United States, the Centers for Disease Control and Prevention announced on Friday.

Dr. Nancy Messonnier, the director of the CDC’s National Center for Immunization and Respiratory Diseases, told reporters on a conference call that the agency was monitoring 63 other potential cases in 22 different states.

“CDC believes the immediate risk to the U.S. public is low at this time, but the situation is evolving rapidly,” Messonnier said.

The new patient is a woman in her 60s who had traveled to Wuhan, China—the epicenter of the deadly virus, which has killed at least 26 people and infected more than 900 globally—in late December. The woman flew back to Chicago on Jan. 13 and, after exhibiting symptoms, contacted her doctor.

“The patient was admitted to a hospital, where infection control measures were taken to reduce the risk of transmission to other individuals,” the CDC said in a statement. “The patient remains hospitalized in an isolation room in stable condition and is doing well.”

The woman has had limited close contact since she returned from China, the statement said, but those individuals will “be monitored for symptoms.”

“It is likely there will be more cases reported in the U.S. in the coming days and weeks,” the agency added in its statement.

The only other confirmed case in the United States, a man in his 30s in Snohomish County, Washington, was still in isolation at Providence Regional Medical Center in Everett, where officials said he was recovering with the help of volunteer nurses. Providence’s chief medical officer, Jay Cook, told reporters on Wednesday that he expected the man could be discharged in the “near future” if he continued to improve.

But even as he recovered, local and federal officials were said to triple the number of his suspected contacts who were being monitored for signs of the illness, from 16 to 43.

Those are individuals who have had “prolonged contact” with the patient—like eating a meal or holding a meeting—in both Snohomish and King counties, according to The Washington Post.

Though local officials provided limited information about who is being monitored, Heather Thomas, Snohomish Health District spokeswoman, told The Daily Beast on Friday that the “evolving investigation” is like “peeling back an onion.”

“Our disease investigators, in coordination with other public health partners, are doing daily symptom monitoring and contact investigations,” Thomas said. That process involves calling to determine if they have a fever, cough, or any other respiratory symptoms.

Eric Toner, a senior scientist with the Johns Hopkins Center for Health Security and the University’s School of Public Health, told The Daily Beast on Friday that the process of “contact tracing is laborious and slow.”

“It takes time to identify and call or visit everyone a person came in contact with over several weeks,” Toner said.

Meanwhile, in China, on the eve of the Lunar New Year, officials shut down public transportation in at least 10 cities, affecting about 33 million people.

“Travel is a major driver in the spread of this infection,” said Dr. Adrian Hyzler, the chief medical officer for Healix International, which provides medical information to organizations whose clients travel internationally. “We have seen the Chinese government enforcing what many in the U.S. and Europe would think of as draconian measures in effectively quarantining over 30 million of its population.”

“It makes sense, but it may be that they have shut the stable door after the horse had bolted,” Hyzler told The Daily Beast on Friday, adding, ‘T his virus has the potential to spread like wildfire.”

Authorities in Wuhan, at the heart of the outbreak, have reportedly begun building a temporary hospital with 1,000 beds on a 270,000-square-foot lot for patients suffering from the virus. That facility was expected to be operational by the end of the month.

Until Friday, the large majority of fatalities had been people older than 60 with pre-existing conditions. But an otherwise healthy 36-year-old man, who was admitted to the hospital on Jan. 9 after falling ill, suffered a cardiac arrest and died on Thursday in Wuhan, according to the Hebei Health Commission. The man had been treated with antibiotics and anti-virus medication.

Though a divided emergency committee convened in Geneva on Thursday by the World Health Organization decided against declaring the outbreak a global health emergency, just one day later, on Friday, Nepal became the latest country to confirm a case of the virus. Anup Bastola, an infectious disease specialist at Sukraraj Tropical and Infectious Disease Hospital in Kathmandu, told The Washington Post that authorities confirmed the diagnosis—of a 32-year-old student who returned home from Wuhan—after sending a sample of the patient’s blood to Hong Kong for testing. He has been discharged from the hospital and none of his close contacts or hospital workers appeared to have shown symptoms of the virus, the paper reported.

Despite the virus’s global spread, mounting death toll, and the dozens of possible cases being monitored by the CDC nationwide, Hyzler said Americans were still at relatively low risk of infection.

“America is prepared for this new respiratory virus,” Hyzler told The Beast. “The U.S. has implemented temperature screening at key entry points to the country, has good access to testing facilities, and [has] the capacity to quarantine the inevitable flow of cases.”