Influenza is surging in the U.S., with doctor visits for flu symptoms at a 15-year high. Why is this flu season so bad?

Influenza cases continue to mount with the virus reaching activity levels in the U.S. not seen for the last 15 years, according to the Centers from Disease Control and Prevention.

There are currently 43 states across the U.S. reporting high or very high flu activity, with some forcing to close schools ...

Influenza cases continue to mount with the virus reaching activity levels in the U.S. not seen for the last 15 years, ...

Influenza cases continue to mount with the virus reaching activity levels in the U.S. not seen for the last 15 years, according to the Centers from Disease Control and Prevention.

Influenza cases continue to mount with the virus reaching activity levels in the U.S. not seen for the last 15 years, ...

So far this flu season, the CDC has reported at least 24 million flu cases in the U.S. That's resulted in around 310,000 hospitalizations and 13,000 deaths. Historically speaking, the month of ...

Influenza cases continue to mount with the virus reaching activity levels in the U.S. not seen for the last 15 years, ...

Levels of influenza nationwide are now at the highest they have been since the peak of the 2009 swine flu pandemic, according ...

NEW YORK (AP) — The U.S. winter virus season is in full force, and by one measure is the most intense in 15 years.