By Jamie Gumbrecht, Michael Nedelman & Jen Christensen

The US Centers for Disease Control and Prevention’s mandatory 14-day quarantine for nearly 200 Americans who returned from Wuhan, China, is the first such order in more than 50 years.

“While we recognize this is an unprecedented action, we are facing an unprecedented public health threat, and this is one of the tools in our toolbox to mitigate the potential impact of this novel virus on the United States,” said Dr. Nancy Messonnier, director of CDC’s National Center for Immunization and Respiratory Diseases, referring to the coronavirus that has sickened thousands in China.

The 195 Americans, many of them diplomats and their families, flew from Wuhan to California on Wednesday. They’ve been staying at March Air Reserve Base since then under a three-day voluntary quarantine.

“We believe that this approach of having a quarantine for the incubation period offers the greatest level of protection for the American public in preventing introduction and spread,” Cetron said. “That is our primary concern.”

CDC officials thanked quarantined individuals for their flexibility. Cetron said most of the passengers were “exuberant and elated to be out of harm’s way” during their journey from Wuhan, and they understand the need for a longer quarantine.

Cetron noted there are cons to quarantine – if they aren’t done properly, if there’s fear and stigma or if people aren’t treated with respect.

“We’re taking every measure possible to ensure these people are treated with dignity and respect,” Cetron said.

One quarantined individual had previously tried to leave the base. CDC officials declined to offer more information about that person.

There are currently six confirmed cases of Wuhan coronavirus in the US – one in Arizona, two in California, two in Illinois and one in Washington.

Some historical context: A quarantine order like this was last used in the 1960s for smallpox evaluation, Dr. Marti Cetron, director of CDC’s Division of Global Migration and Quarantine, said Friday during a telebriefing with reporters.