And why does it feel so much worse than a cold?
The vaccine is the "first and most important step in protecting against influenza and its potentially serious complications," according to the CDC.
Flu season may be winding down but it isn't over.
The strain to which you lost your flu virginity will always hold a special status.
Several factors could make the athletes more susceptible to the virus.
Younger "baby boomers" are being particularly hard-hit by the flu this year.
School districts have rushed to clean every "Lego and Potato Head" as absences this flu season reach abnormal levels.
The number of states reporting widespread flu activity nearly doubled this week.