Orange County health officials reported four new cases of COVID-19 over the weekend, bringing the number of people in the county infected with the novel coronavirus up to 17 as of Sunday, March 15.

Three cases were reported on Sunday, including two that did not appear to be related to travel or people with previously documented cases of the illness, said Molly Nichelson, public information manager for the County of Orange.

The third was linked to contact with a known patient. A fourth case was identified on Saturday, and was related to travel abroad, according to statistics posted by the agency.

Officials at USC announced Sunday that a student of the school who had been travelling abroad was diagnosed with COVID-19 upon returning home to Orange County. Nichelson declined to comment on that report, or provide further details regarding where the student might have contracted the illness, citing privacy concerns.

HCA officials have tested 160 people for signs of the novel coronavirus, according to the agency website. As of Sunday, officials had 1,098 kits on hand to examine samples from Orange County residents who may have been infected. People older than 60, and those with chronic medical conditions like lung or heart disease and diabetes are most susceptible to the pathogen.

“We now have documented community transmission of COVID-19 in Orange County, which means there is risk of exposure anywhere in the county,” Nichelson said.

There are approximately 5.3 million Californians over the age of 65, Gov. Gavin Newsom said during a news conference Sunday.

“We are prioritizing their safety because of their unique vulnerabilities to the virus,” Newsom said.

County Health Officer Dr. Nichole Quick joined the Orange County Board of Supervisors in declaring a state of emergency on Feb. 26 in response to a global pandemic of the novel coronavirus. Meanwhile, all 615 schools within the jurisdiciton of the Orange County Department of Education were ordered to close for two weeks after dismissal bells rang on Friday, March 13. On that day, Health Care officials announced the first instance of community spread of the virus in Orange County.

The governor has advised the cancellation of large events across the state and urged Californians to limit their social interaction. On Sunday he issued further guidelines calling for residents over the age of 65 to isolate themselves at home, as well as the closure of all bars and pubs. Restaurants may remain open, but are recommended to cut their normal occupancy in half.

“We still have the capacity to be productive in this society,” Newsom said. “But we need to protect those most vulnerable.”