COVID-19 vastly accelerated vaccine skepticism, such that even routine childhood immunizations, including shots that had largely eliminated measles, are now being questioned. Misinformation can be as contagious as disease, undermining faith in institutions, jeopardizing public health and safety, and distorting clinical decision making. Come watch a live demonstration that reveals how viral spread actually happens. To gain control over social media and the bots that spread fake news, we need to track falsehoods rigorously and develop communication systems to counter them swiftly. Big Data and machine learning can help to identify the pathways by which inaccuracies and rumors proliferate and inform effective interventions that can block them.