And in our media-connected world, fear spreads even more quickly than infections. Fueled by television and social media, fears of infectious diseases, whether rational or unwarranted, drive behavior and policy changes, triggering travel bans, quarantines, and blocks on trade that can quickly escalate beyond what is scientifically justified. So though medical advances are helping us contain the loss of life from infectious-disease outbreaks, our vulnerability to economic damage seems magnified.