Don't think about a white bear.

What did you just see in your mind's eye? If the answer was "a white bear," you'll have grasped one of the problems facing public health officials in talking about the risks from the COVID-19 coronavirus. The message most experts will want to convey is, naturally, "Don't panic." But it's almost impossible for humans to hear that instruction without its alarming echo: "Panic."

If COVID-19 turns into a global pandemic, as looks increasingly likely, this problem is going to crop up again and again. Doctors want to convey information that will help people limit their own risks and minimize the burden on health systems. At the same time, they worry that the very act of sharing information will encourage people to act as if they're in the grip of an emergency.