China’s coronavirus has infected 22 people in a nursing home in DuPage County, Illinois, forcing officials to declare an emergency.

The infection has hit 18 elderly patients and four workers, Illinois Gov. J.B. Pritzker announced March 17, according to Patch.com

The bad news came two days after officials revealed the first infection at the nursing home. The Chicago Tribune reported March 15:

DuPage County announced its first case of coronavirus, a woman in her 60s, during a press conference with Governor J.B. Pritzker on Saturday. The woman, who is a resident of Chateau Nursing and Rehabilitation Center in Willowbrook, remains hospitalized and is in stable condition, said Ron Nunziato, CEO of Extended Care LLC, a consulting firm that works with the Willowbrook facility. “We do not know how this happened to this resident,” DuPage County Public Health Department Executive Director Karen Ayala said. “However, since she hasn’t traveled or apparently had contact with another COVID case, we are conjecturing at this point that this is another example of community spread.”

Presidnet Donald Trump and health officials have warned state and local officials to try to shield nursing homes from the disease, which kills rough 20 percent of people aged 80 and above. On March 13, Trump told a press conference:

Anyone can be a carrier for the virus and risk transmission to older Americans and those with underlying health conditions, and those who are most at risk. They have not done very well. … Especially if they have a health problem, they have not done well. We must take all precautions.

The disease has already killed numerous residents of a nursing home in Washington state. Business Insider reported March 11:

Before the coronavirus hit the Life Care Center in Kirkland, Washington, 120 seniors lived there. Now there are fewer than 50. The long-term care facility, about 20 minutes north of Seattle, has been battling a coronavirus outbreak for weeks. Since the outbreak started, 26 of the center’s residents have died, 13 of whom were confirmed to have COVID-19, the disease the coronavirus causes. Some others who died have not yet been tested.

The Kirkland deaths came at the very start of the epidemic when there was no shortage of hospital resources.

Illinois officials said they are trying to identify the source of the infection, before the source — likely a person — infects another site:

Individuals who have come in close contact with the woman have been given both verbal and written instructions on what to do. Ayala defined close contact as being within six feet of the woman for at least 10 minutes. Though Ayala could not put a number to the number of people who had come in close contact with the woman, Ayala noted that the average in such cases is about 90 people per case.