During the 2017-2018 flu season over 60 million Americans were infected with influenza and an estimated 50,000 died. Why has there been so much sickness when a vaccine does exist? Producer Chris LeBoa investigates the process and guesswork that goes into creating the flu shot each year and what is being done to take guesswork out of future vaccines.

Featuring: Corrie Dekkar, Julie Parsonnet, Julie Fogarty