Officials including L.A. Department of Public Health officials, Los Angeles Mayor Eric Garcetti and L.A. County Supervisors Kathryn Barger and Janice Hahn said the declaration would allow greater coordination among various levels of government, stressing that they were acting out of "an abundance of caution'' and not panic.
In addition, the county Department of Public Health announced a local health emergency in response to the increase in cases.
Including a previous case, there are a total of 7 cases across the county.
The cities of Long Beach and Pasadena, which both have their own public health departments separate from the county, also declared public health emergencies, though there are no confirmed cases in either city.
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"This declaration of a local emergency will facilitate our efforts to coordinate with all our partners and jointly implement effective strategies to protect our residents," said Supervisor Kathryn Barger.
One of the infected individuals was hospitalized, while the other five are isolated at home, closely monitored by health department officials.
Public health officials said they are aware of an assumed exposure source for all six cases, which rules out the possibility that they were infected through community spread. Three of the infected recently traveled together in northern Italy, which has been hit hard by the virus.
Two others are family members who were in close contact with another family member who lives elsewhere and tested positive for novel coronavirus, according to officials. The sixth individual is a medical professional who worked as a passenger screener at Los Angeles International Airport. That person last worked at the airport on Feb. 21 and then felt the first symptoms more than a week later and is now under self-quarantine at home.
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"While we are announcing new cases, and we will continue to announce new positive cases, the risk for individuals to be exposed to novel coronavirus here in LA County still remains relatively low," said Dr. Barbara Ferrer, director of the LA County Department of Public Health.
"That doesn't mean we shouldn't do everything we can to protect ourselves. But it does mean we have no known community spread."
The county's second case of COVID-19 was confirmed on Tuesday by Kaiser Permanente, who is overseeing the care of the patient, currently in self-isolation and being treated as an outpatient, a spokesperson said. Additional details regarding the case were not available.
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News of the new L.A. County cases came on the heels of Orange County health officials announcing Tuesday that two people tested positive for the novel coronavirus, though the diagnoses were described as "presumptive positive," pending final confirmation from the Centers for Disease Control and Prevention.
County health officer Dr. Nichole Quick said the county recently improved its ability to perform COVID-19 testing and therefore "we expect to see more cases here in Orange County."
Nine deaths have been reported in the United States, all in Washington state. More than 93,000 cases of the illness have been confirmed globally.
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