For the professionals who try to manage homeland-security threats, reassuring the public after a natural disaster or terrorist attack—or amid a coronavirus outbreak like the one the world now faces—is just part of the job. I am a former federal and state homeland-security official. I study safety and resiliency issues in an academic setting, advise companies on their emergency-response plans, and trade ideas with people in public health, law enforcement, and many other disciplines. Since the beginning of the disease now known as COVID-19, I’ve also been receiving more and more text messages from nervous relatives and friends. The rash decisions that…