Just as you never forget your first love, you—or rather, your immune system—will never forget your first flu. But that first flu just might be why our flu vaccines, especially lately, don’t work as well as they should. Almost everyone is exposed to influenza at a very young age, and this first infection likely has lifelong consequences. It sends the immune system down a path that skew immune responses to subsequent exposures to influenza—and to influenza vaccines—for the rest of a person's life.
