More than a century ago, millions of people around the world died in a massive influenza pandemic. The so-called "Spanish flu" outbreak of 1918 revealed a truth about viruses: they don't just infect us biologically. They also detect fissures in societies and fault lines between communities. Historian Nancy Bristow says this remains true today, as we continue to grapple with the COVID-19 pandemic.This week, we revisit our 2020 conversation with Bristow, and consider what history can tell us about human behavior during public health crises.