Two new coronavirus cases in King County, Washington, are associated with a nursing home, raising the specter of an outbreak among people particularly susceptible to complications from an infection.

One of the patients, a woman in her 70s, is in serious condition, said Jeff Duchin, Seattle and King County health officer. The other patient is a woman in her 40s who is health care worker at the facility, Life Care Center of Kirkland.

Washington also reported the first U.S. coronavirus death Saturday, a man in his 50s with underlying health conditions, the day after Oregon announced its first case of coronavirus. He is not tied to the nursing home.

The U.S. Centers for Disease Control and Prevention is sending a team of experts to help local officials investigate the cases. Officials have already found that 27 of 108 residents at the nursing home report some symptoms of respiratory illness, Duchin said, and 25 of the 180 staff do, too. Health officials are investigating these cases but they don’t yet know if the people are sick with coronavirus.

The two confirmed cases at the nursing home and the man who died of coronavirus brought to 22 the number of infections in the United States discovered by the health care system, the CDC said.

CORONAVIRUS IN OREGON: FULL COVERAGE

For U.S. residents at large, the risk of a COVID-19 infection continues to be low, a CDC official said Saturday, and that includes those in nursing homes. But the federal government is ramping up its work, said Dr. Nancy Messonnier, director of the Center for the National Center for Immunization and Respiratory Diseases.

“We are facing a historic public health challenge,” Messonnier said.

There are now enough kits to test more than 75,000 people, she said. If the spread broadens, Messonnier said communities might have to take steps to prevent close contact between people, a method called social distancing.

Oregon announced its first presumptive coronavirus case Friday – in a person who works at Forest Hills Elementary School in Lake Oswego. Few people had close contact with the person, the school district superintendent said Saturday.

As of Friday, the patient was at the Kaiser Permanente Westside Medical Center in Hillsboro.

A second Oregon resident who was under investigation for the illness, unrelated to the Forest Hills employee, tested negative on Saturday, officials said. At least seven other tests are pending and 88 people are being monitored for the disease, according to the Oregon Health Authority.

Forest Hills Elementary will be closed through Wednesday to deep-clean the school and allow health investigators to talk to the few people who had close contact with the employee and may have become infected. The person doesn’t have a job with much student contact.

Oregon’s sole coronavirus infection is one of a handful in the United States that, because they are of unknown origin, are particularly alarming for health officials. The majority of the more than 60 U.S. cases have been traced to travel abroad.

MORE CORONAVIRUS NEWS:

Washington coronavirus: Governor declares state of emergency

Oregon coronavirus: What we know so far

Coronavirus in Oregon: Second person under investigation tests negative for illness

Best advice for those worried about coronavirus in Oregon: Stay calm

Lake Oswego church taking precautions in light of Oregon coronavirus case

-- Fedor Zarkhin

fzarkhin@oregonian.com

desk: 503-294-7674|cell: 971-373-2905|@fedorzarkhin

Subscribe to Oregonian/OregonLive newsletters and podcasts for the latest news and top stories.