SAN FRANCISCO (CBS SF) — Health officials have confirmed at least five cases of coronavirus were transmitted within UCSF’s Helen Diller Medical Center, in Parnassus Heights.

Two patients, along with three workers who cared for them have tested positive for COVID-19, according to UCSF. Both patients tested negative before they were admitted.

On Tuesday, the hospital issued a statement saying the patients shared a room to date neither has symptoms. The workers, so far, have only mild symptoms.

“We have isolated these patients and employees, and are working to identify, test and quarantine other individuals who may have been exposed to them, or who have symptoms,” said the statement.

So far, 28 employees and 15 patients are quarantining, “out of an abundance of caution.”