What is the Flu?
The flu is a contagious respiratory illness caused by Influenza viruses. It can infect the nose, throat, and sometimes the lungs. Symptoms can be mild to severe, and it can also lead to death. Although avoiding close contact with people who are sick, staying home when you are sick, covering your mouth and nose with a tissue when coughing or sneezing and washing your hands often to protect you from germs, may help to prevent getting the flu. Medical experts agree that getting a flu shot, or flu vaccine, is the single most effective way to protect us and others from the illness.
Each year between 3 and 11% of the U.S. population gets infected and develops flu symptoms. Severe symptoms, hospitalization and death occur mainly among high-risk groups. Most flu-related deaths occur in adults 65 years and older.
There are 4 types of influenza viruses, types A, B, C and D. Influenza A and B cause seasonal epidemics of disease. Influenza virus type C may spread from person to person through respiratory droplets. Influenza virus type D primarily affects cattle and can spread to other animals, but it was not recorded that it caused illness in people.
Because the structure of flu viruses is constantly changing, flu vaccine must be updated each season.2,3
