“We cannot hermetically seal off the United States to a virus,” Alex Azar, the secretary of health and human services, told a Senate panel. “And we need to be realistic about that.”

There are currently at least 57 people with the virus in the U.S., all of whom have either recently traveled to Asia or are closely connected to others who have. Infectious disease experts stressed that people shouldn’t panic. Here’s some of their advice.

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Related: The U.S. military said today that a soldier in South Korea had tested positive for the virus, the first American service member to become infected. Here are the latest updates and maps of where the virus has spread.

Another angle: In China, where the virus originated, the Communist Party has turned to propaganda to confront the biggest challenge to its legitimacy in decades. But our columnist reports that young people are openly questioning the official message. “News Coverage Should Stop Turning a Funeral Into a Wedding,” read the headline on one blog post.