SARS-CoV-2, like other zoonotic diseases, originated in animals before “spilling over” into humans. Dr. Raina Plowright of Montana State University studies these events and the complex series of things that have to happen for them to take place. Dr. Plowright talks with Dr. Josh Sharfstein about how these occur, why these events are relatively rare, and what’s important to understand about them so we can learn how to prevent them from happening.