Influenza (Flu)

What is influenza (flu)?


Influenza viruses continually change (mutate). Because the virus changes, people can get the flu no matter what their age. The process works like this:


  2. The virus changes.


  4. The person becomes infected again.

The older antibodies can, however, give some protection against getting the flu again. Currently, 3 different influenza viruses circulate worldwide. Vaccines given each year to protect against the flu contain the influenza virus strain from each type that is expected to cause the flu that year.

What are the facts about the flu?


What causes the flu?


What are the symptoms of the flu?

The following are the most common symptoms of the flu:

  • Fever

  • Headache

  • Runny or stuffy nose

  • Cough

  • Severe aches and pains

  • Fatigue or feeling very tired

  • Sometimes a sore throat

What is the treatment for the flu?

Treatment may include:

  • Medications to relieve aches and fever

  • Medications for congestion and nasal discharge

  • Bed rest and increased intake of fluids


How can the flu be prevented?

A new influenza vaccine is available each year. You should get the vaccine as soon as it is available in your area.

The Center for Disease Control and Prevention (CDC) recommends that infants over the age of 6 months and all children and adults get flu shots every year.

Some people are at increased risk of developing serious complications from the flu. It is extremely important that these people get the vaccine.  They include those with:

  • Long-term heart and lung conditions

  • Other serious medical conditions such as

    • Endocrine disorders, like diabetes

    • Kidney or liver disorders

    • Weak immune system from disease or treatment; for example those with HIV or AIDS or taking long-term steroids or medications to treat cancer

    • Blood disorders such as sickle cell disease

  • It is also very important that others that have an increased risk of being exposed to the flu or are around people with increased risk of complications get the vaccine. They are:

    • Health care providers and other staff that provide care in hospitals, nursing homes, hone health, and other facilities

    • Household members, including children or people in high-risk groups

Types of vaccines

The flu vaccine is available as a shot and as a nasal spray. Your health care provider will determine which vaccine is right for you.

The shot is available in a few different forms. There is a high-dose vaccine for those over 65 and a vaccine for those with egg allergies. It is safe for most people. Talk with your provider if you have had

  • A severe allergic reaction to a previous flu vaccine

  • Guillain-Barre syndrome (a severe paralyzing condition)

The nasal spray is recommended for people from 2 to 49 years old. It should not be given to adults who:

  • Are pregnant

  • Have weak immune systems

  • Have egg allergy

  • Will be in close contact with someone with a weak immune systems

  • Have taken antiviral medication in the past 2 days

Antiviral medications are also available to prevent the flu in people who have been in close contact with others with the flu. Contact your health care provider if you have been exposed to someone with the flu.

Following these precautions may also be helpful:

  • When possible, avoid or limit contact with people who have the flu or symptoms of the flu.

  • Frequent handwashing helps to lessen the risk of the risk of infection. Wash them well for 15 to 20 seconds.

  • Cover your nose and mouth when coughing or sneezing. It is best to use tissues. Then wash your hands.

How effective is the flu vaccine?

Vaccine effectiveness varies from year to year. Vaccine effectiveness also varies from one person to another, depending on factors such as age and overall health.

What are the side effects of the flu vaccine?

The flu vaccine is safe. Vaccine safety is closely watched by the CDC and the Food and Drug Administration (FDA), and hundreds of millions of flu vaccines have been safely given across the country for decades.

The flu vaccine can't give you the flu. The most common side effects from a flu shot are soreness where the shot was given and maybe a slight fever or achiness. The nasal spray flu vaccine might cause congestion, runny nose, sore throat, or cough. These side effects are mild and don't last long.

When should I get a flu shot?

The CDC recommends getting the flu shot every year, as soon as it becomes available in your community. Flu season can begin as early as October and most commonly peaks in the U.S. in January or February. The flu shot takes 1 to 2 weeks to become effective.


If you get the vaccine, it is still possible to get the flu. People who have had the flu shot tend to have milder symptoms if they do get the flu.

Is traveling safe during the flu season?

Because the flu is a highly contagious infection usually spread by droplets from by an infected person who is coughing or sneezing, travelers are at increased risk of getting the flu.
