Overview: What is the flu?

Influenza (flu) is a contagious respiratory illness caused by influenza viruses that occur in the annual flu season. It can cause mild to severe illness. Serious outcomes of flu infection can result in hospitalization or death.

Most experts believe that flu viruses spread mainly by tiny droplets made when people with flu cough, sneeze or talk.

Getting a flu vaccine and taking steps to reduce the spread of the virus are more important than ever during 2020-2021 to protect yourself and the people around you from flu, and to help reduce the strain on healthcare systems responding to the COVID-19 pandemic.

What are the symptoms of the flu?

Influenza (flu) can cause mild to severe illness, and at times can lead to death. Flu is different from a cold. Flu usually comes on suddenly. People who have flu often feel some or all of these symptoms:

  • fever (not everyone with the flu with have a fever) or feeling feverish/chills
  • cough
  • sore throat
  • runny or stuffy nose
  • muscle or body aches
  • headaches
  • fatigue (tiredness)
  • some people may have vomiting and diarrhea, though this is more common in children than adults.

Getting vaccinated reduces your chances of getting the flu and can lessen the severity if you are infected.

Who should get a flu shot?

Everyone 6 months and older should get a flu vaccine every season with rare exceptions. Vaccination is particularly important for people who are at high risk of serious complications from influenza. More information about the flu shot itself can be found here.

When should you get a flu shot?

Here are helpful guidelines to follow for the timing of a flu shot:

  • Vaccine should be administered by the end of October.
  • It takes about two weeks after vaccination for antibodies to develop in the body and provide protection against flu.
  • Vaccination should continue to be offered throughout the flu season, even into January or later.

Where can you get a flu shot?

Courtesy of the Centers for Disease Control and Prevention (CDC), please use the “Vaccine Finder” box to the right for options of where to get a flu shot near you.

What is the difference between the flu, a cold, allergies or COVID-19?

The Kansas Department of Health and Environment has produced this helpful infographic to help you distinguish which illness you may have at any given time. View infographic.

How can you stop the spread of the flu?

Take these steps to help avoid spreading the flu this season:

  • If you are sick – stay home! If you have a fever, stay home for at least 24 hours after the fever is gone (without using fever-reducing medicine).
  • Wear a mask to reduce the spread of germs!
  • Cover your mouth and nose with a tissue when you cough or sneeze.
  • Throw used tissues in the trash.
  • If you don’t have a tissue, cough or sneeze into your elbow, not your hands.
  • Wash your hands!  This is especially true after you cough or sneeze. Hand washing should be done for at least 20 seconds with soap and warm water.
  • If soap and water are not readily available, use an alcohol-based hand sanitizer that contains at least 60% alcohol to clean hands.

Additional Resources:

Flu fact sheets:

Downloadable posters:

You can also access fact sheets from as many as 12 different languages, courtesy of the CDC.


If you’re interested in learning more about the flu and how to prevent it, KHF has compiled a list of articles from sources across the country:

Connect With Us

Sign Up for Health Happenings

Every month, our electronic newsletter, Health Happenings, features a story about a focus area, grant, partnership or program involving the Foundation.