Influenza is surging in the U.S., with doctor's visits for flu symptoms at a 15-year high. Why is this flu season so bad?
Flu cases soar across the US; Sacramento sees highest flu-related medical visits since 2009. Learn prevention tips and why vaccination rates matter.
Influenza levels in the US are the highest they've been in 15 years amid winter weather and a second wave of the virus.
The U.S. winter virus season is in full force, and by one measure is the most intense in 15 years.
With data showing a significant rise in flu cases nationwide, medical experts are describing it as the worst flu season since ...