SPOKANE, Wash. (AP) — Authorities in Washington state have reported that more than half of the inmates at Geiger Corrections Center have tested positive for COVID-19 and are being kept in isolation and quarantined.

Spokane County Detention Services said that 79 of the 138 inmates at the facility tested positive as of Friday, The Spokesman-Review reported. The Airway Heights facility, located west of Spokane, has capacity for 360 inmates.

Department officials also said that 11 detention center employees tested positive.

The number of infections is thought to be far higher because many people have not been tested, and studies suggest people can be infected with the virus without feeling sick.

“We’ve really got our focus set right now on our Geiger facility,” Detention Services Director Mike Sparber said. “We have a strategy for downtown, but we’re just not seeing what we’re seeing at Geiger.”

The department had confirmed nine COVID-19 cases in inmates the week before, officials said.

Spokane Regional Health District Epidemiologist Betsy Bertelson said inmates who have not tested positive are now being tested twice weekly and employees are being tested weekly. New inmates are isolated for two weeks before being integrated with others.

For most people, the coronavirus causes mild or moderate symptoms, such as fever and cough that clear up in two to three weeks. For some — especially older adults and people with existing health problems — it can cause more severe illness, including pneumonia, and death.