Influenza, also known as the flu, is a contagious respiratory disease that is caused by influenza viruses. Influenza viruses infect the respiratory tract (nose, throat, and lungs) in humans. The flu is different from a cold, mainly because the symptoms and complications are more severe. Influenza usually comes on suddenly and may include these symptoms: fever, headache, malaise (a feeling of being ill and without energy that can be extreme), cough, sore throat, nasal congestion and body aches.
A lot of the illness and death caused by the influenza virus can be prevented by a yearly influenza vaccine. Most individuals 6 months of age and older should get the influenza vaccine every year. It is especially important for people in high-risk groups and people who are in close contact with those at high risk to get an influenza vaccine every year as recommended by CDC’s Advisory Committee on Immunization Practices (ACIP).
Influenza vaccine can be given to most individuals 6 months of age and older to protect against influenza. Persons who provide important community services (such as police, fire department personnel, emergency medical services) should consider getting an influenza vaccine so that those services are not disrupted during an influenza outbreak.
- www.Flu.gov
One-stop access to U.S. Government H1N1, avian and pandemic flu information
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Content current as of:
03/02/2026
