Flu FAQs

Flu Immunizations FAQs


Why Get the flu shot?

Influenza (“flu”) is a contagious disease that spreads around the United States every winter, usually between October and May.

Flu is caused by the influenza virus, and can be spread by coughing, sneezing, and close contact.

Anyone can get flu, but the risk of getting flu is highest among children. Symptoms come on suddenly and may last several days. They can include:

  • fever/chills
  • sore throat
  • muscle aches
  • fatigue
  • cough
  • headache
  • runny or stuffy nose

Flu can also lead to pneumonia, and make existing medical conditions worse. It can cause diarrhea and seizures in children.

Each year thousands of people in the United States die from flu, and many more are hospitalized.

Flu vaccine is the best protection we have from flu and its complications. Flu vaccine also helps prevent spreading flu from person-to-person.

Everyone six months of age and older should get a flu vaccine every year. It is especially important for kids with asthma or diabetes to get vaccinated to help decrease their risk of serious complications from the flu. Preteens and teens should get a flu vaccine in the fall, or as soon as it is available each year.

Flu can make some people much sicker than others. These people include young children, people 65 and older, pregnant women, and people with certain health conditions – such as heart, lung or kidney disease, or a weakened immune system. Flu vaccine is especially important for these people, and anyone in close contact with them.

Some people should not be vaccinated without first consulting a physician. They include:

  • People who have a sever allergy to chicken eggs.
  • People who have had a severe reaction to an influeza vaccination in the past.
  • People who developed Guillain-Barré syndrome (GBS) within 6 weeks of getting an influenza vaccine previously.
  • Children less than 6 months of age (influenza vaccine is not approved for use in this age group).
  • People who have had a moderate or severe illness with a fever should wait to get vaccinated until their symptoms lessen.

If you have questions about whether you should get a flu vaccine, consult your health-care provider.

You can receive flu vaccine as soon as vaccine becomes available. Early vaccination of children younger than age 9 years who need 2 doses of vaccine can be helpful in assuring routine second doses before the influenza season begins.

Flu vaccines CANNOT cause the flu. The viruses in flu vaccines are either killed (the flu shot) or weakened (the nasal spray vaccine).

There are several reasons the misconception persists:

(1) Less than 1% of people who are vaccinated with the injectable vaccine develop flu-like symptoms, such as mild fever and muscle aches, after vaccination. These side effects are not the same as having influenza, but people confuse the symptoms.
(2) Protective immunity doesn’t develop until 1–2 weeks after vaccination. Some people who get vaccinated later in the season (December or later) may get influenza shortly afterward. These late vaccines develop influenza because they were exposed to someone with the virus before they became immune. It is not the result of the vaccination.
(3) To many people “the flu” is any illness with fever and cold symptoms. If they get any viral illness, they may blame it on the flu shot or think they got “the flu” despite being vaccinated. Influenza vaccine only protects against certain influenza viruses, not all viruses.
(4) The influenza vaccine is not 100% effective, especially in older persons. For more information on this topic visit the CDC website.

Mild problems following inactivated flu vaccine:

  • soreness, redness, or swelling where the shot was given
  • hoarseness; sore, red or itchy eyes; cough
  • fever
  • aches
  • headache
  • itching
  • fatigue

If these problems occur, they usually begin soon after the shot and last 1 or 2 days.

No. It takes about two weeks after vaccination for antibodies to develop in the body and provide protection against influenza virus infection. In the meantime, you are still at risk for getting the flu. That’s why it’s better to get vaccinated early in the fall, before the flu season really gets under way.