The Centers for Disease Control and Prevention on Wednesday confirmed an infection in California that would represent the first U.S. person to contract the virus despite not visiting a foreign country recently or coming in contact with an infected patient.
"At this time, the patient's exposure is unknown," the CDC said in a statement. "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. Community spread means spread of an illness for which the source of infection is unknown. It's also possible, however, that the patient may have been exposed to a returned traveler who was infected."