Public health crises have spawned conspiracy theories as far back as when the Black Death ravaged Europe in the 1300s, as people desperately try to make sense of the chaotic forces disrupting their lives. While modern science offers a better understanding of how diseases infect people and how to contain them, COVID-19 conspiracy theories are spreading rapidly via social media, unreliable news outlets and from our own political leaders, including U.S. President Donald Trump. The result: many Americans now believe pandemic-related conspiracy theories—and, alarmingly, those same people are less likely to take steps to prevent the virus from spreading.