How is flu season defined? what are the criteria for this definition?

The flu, also known as the influenza virus, is diagnosed year-round in the United States. Fall and winter seasons are when the greatest impact is usually seen and, therefore, is considered the "flu season." Influenza activity has a period of greatest activity between December and February, but the activity can last until May.

Every year at the beginning of the fall season, people are encouraged to get a flu shot.

CDC data on influenza vaccine:

• 116 million doses of influenza vaccines have been distributed.

CDC

(Centers for Disease Control and Prevention) recommends that all persons 6 months and older receive the influenza vaccine at the end of October.

• Influenza vaccination offers important benefits

condenser is used to focus in the light microscope.