Science Behind The News: Influenza & Flu Vaccines

Every flu season, Americans battle coughs, fevers and body aches. The flu is a respiratory illness caused by a virus, a pathogen that causes disease in the human body. To understand how the flu is caught, spread and treated, Duke University's Katia Koelle explains the biology of a virus and how it is transmitted. "Science Behind the News" is produced in partnership with NBC Learn. Provided by the National Science Foundation & NBC Learn