Health and Human Services Secretary Alex Azar testifies before a House Appropriations subcommittee on Capitol Hill in Washington on Wednesday. Susan Walsh/AP

The 15th coronavirus case in the US, which was announced earlier on Wednesday, may be the first example in the country of “community spread,” where the patient did not have “relevant travel history or exposure to another known patient," said the US Centers for Disease Control and Prevention (CDC).

The patient is a resident of Solano County, California, and their “exposure is unknown.”

“It’s possible this could be an instance of community spread of COVID-19, which would be the first time this has happened in the United States,” the CDC said.

What this means: Community spread means the virus begins moving through a community and the “source of the infection is unknown,” the agency said.

“It’s also possible, however, that the patient may have been exposed to a returned traveler who was infected,” the CDC said.

The patient is now being treated in Sacramento.

US cases: There are 42 cases in the US that are passengers who were evacuated from the Diamond Princess cruise ship, 14 cases who recently returned from China or are the spouse of a recent returnee, and three people who were repatriated from China, making the national total 60 cases.