It’s the first such order in more than 50 years, made as officials work to contain the outbreak that has so far killed at least 213 people and infected more than 9,000 others in China, most of them in Wuhan. Outside mainland China, there are 140 confirmed cases, including six in the United States.

“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…