The winter flu season features two types of influenza. Here's what you need to know about them and how they differ.

Flu infections are at or near their highest levels in at least 15 years and are still rising, the Centers for Disease Control and Prevention says.

The U.S. winter virus season is in full force, and by one measure is the most intense in 15 years.

More than 24 million people have had seasonal flu this season, according to estimates from the Centers for Disease Control ...

In a breakthrough for influenza research, scientists have discovered immune cells that can recognize influenza (flu) viruses ...