Three new novel coronavirus cases, including two who were aboard the Grand Princess cruise ship docked off the coast of San Francisco, have been confirmed in Contra Costa County, health officials said Friday.

The three patients are currently quarantined in their homes, according to the Contra Costa County Health Services Department.

In addition to the two cruise ship passengers, the third patient is confirmed to have had close contact with a coronavirus patient in another jurisdiction.

The three confirmed cases of the virus brings the total to four in Contra Costa County. On Tuesday, health officials confirmed the county's first case of the virus. That patient, who is being treated at a local hospital, is not known to have a travel history that put them at risk to contract the virus and did not have close contact with another patient prior to showing symptoms.

County health officials will hold a news conference at 2 p.m. Friday afternoon at Contra Costa Health Services, 1220 Morello Ave. in Martinez. They plan to discuss the three new cases as well as a set of community guidelines for how to slow the virus' spread.

Officials advise residents older than 50 and people with underlying medical conditions to avoid large crowds and events to reduce their risk of contracting the virus.

As of Friday morning, at least 60 cases of the virus have been confirmed in California, according to state health officials.