Tracking flu activity across the US

The percentage of outpatient visits for influenza-like illness for the is .

Note: Influenza-like illness is defined as fever (≥100°F) plus cough and/or sore throat. Earlier seasons may show partial-year data, as annual surveillance was not consistently available outside of the traditional flu season. The 2009-10 season is excluded. Data current as of .

Source: US Centers for Disease Control and Prevention

Graphic: Matt Stiles, CNN