More than three years since the start of the COVID pandemic, infectious disease experts are studying other viruses with pandemic potential. Their goal is to understand how pandemics begin and how they can be prevented.This is the focus of the NPR series "Hidden Viruses: How Pandemics Really Begin." In this episode, NPR's Ari Daniel takes us to Bangladesh, where researchers studied a dangerous virus called "Nipah" and how it spreads. In participating regions, you'll also hear a local news segment to help you make sense of what's going on in your community.Email us at considerthis@npr.org.