On this week's episode, we review the history of the flu. We explore ancient flu pandemics, the "Spanish flu" of 1918, and the state of the flu today. In addition, we explore why the flu is so hard to achieve lasting immunity from infection or vaccination. We also get into the nitty-gritty of what the flu is, how it works, and what's being done in the world of science and clinical research to help protect us better.