The current study investigated  Health Awareness about the Causes of Influenza  among the Youth in Riyadh City, The results were reached that: Influenza is a simple viral infection that spreads easily among humans. It attacks the common system. A person becomes infected through the nose and mouth and reaches the lungs. Its severity ranges from mild to severe, and it affects all age groups.

• It is divided into four main types, some of which infect humans, and others infect animals:

• Influenza A virus and influenza B virus: They infect humans and are the causes of seasonal influenza infections that spread in the winter season.
• Influenza C virus: infects humans, and is the cause of influenza infections throughout the year.
• Influenza D virus: It infects livestock and cannot be transmitted to humans.

• There are subtypes of influenza A virus, and they differ according to the protein (H or N) that coats the virus, as there are 18 types of H protein and 11 types of N protein.

Transportation methods:

• Inhaling droplets flying in the air when an infected person sneezes or coughs.
• Touching surfaces contaminated with the virus; Then touch the eyes, mouth and nose.