Influenza Vaccine Information

Why Get Vaccinated?

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

Flu is caused by influenza viruses, and is spread mainly by coughing, sneezing, and close contact.

Anyone can get flu.  Flu strikes suddenly and can last several days. Symptoms vary by age, but can include:

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

Flu can also lead to pneumonia and blood infections, and cause diarrhea and seizures in children. If you have a medical condition, such as heart or lung disease, flu can make it worse.

Flu is more dangerous for some people. Infants and young children, people 65 years of age and older, pregnant women, and people with certain health conditions or a weakened immune system are at greatest risk.

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

Flu vaccine can:

  • keep you from getting flu,
  • make flu less severe if you do get it, and
  • keep you from spreading flu to your family and other people.

Inactivated and recombinant flu vaccines:

A dose of flu vaccine is recommended every flu season. Children 6 months through 8 years of age may need two doses during the same flu season. Everyone else needs only one dose each flu season.

Some inactivated flu vaccines contain a very small amount of a mercury-based preservative called thimerosal. Studies have not shown thimerosal in vaccines to be harmful, but flu vaccines that do not contain thimerosal are available.

There is no live flu virus in flu shots. They cannot cause the flu.

There are many flu viruses, and they are always changing. Each year a new flu vaccine is made to protect against three or four viruses that are likely to cause disease in the upcoming flu season. But even when the vaccine doesn’t exactly match these viruses, it may still provide some protection.

Flu vaccine cannot prevent:

  • flu that is caused by birus not covered by the vaccine, or
  • illnesses that look like flu but are not.
It takes about 2 weeks for the protection to develop after vaccination, and protection lasts through the flu season.

Some people should not get this vaccine:

Tell the person who is giving you the vaccine:

  • If you have any severe, life-threatening allergies.
If you ever had a life-threatening allergic reaction after a dose of flu vaccine, or have a severe allergy to any part of this vaccine, you may be advised not to get vaccinated.  Most, but not all, types of the flu vaccine contain a small amount of egg protein.
  • If you ever had Guillain-Barre' Syndrome (also called GBS).
Some people with a history of GBS should not get this vaccine.  This should be discussed with your doctor.
  • If you are not feeling well.
It is usually okay to get flu vaccine when you have a mild illness, but you might be asked to come back when you feel better. 
Risks of a vaccine reaction:

With any medicine, including vaccines, there is a chance of reactions. These are usually mild and go away on their own, but serious reactions are also possible.

Most people who get a flu shot do not have any problems with it.

Minor problems following a flu shot include:

  • 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.

More serious problems following a flu shot can include the following:

  • There may be a small increased risk of Gullain-Barre' Syndrome (GBS) after inactivated flu vaccine.  This risk has been estimated at 1 or 2 additional cases per million people vaccinated.  This is much lower than the risk of severe complications from flu, which can be prevented by the flu vaccine. 
  • Young children who get the flu shot along with pneumococcal vaccine (PVC13) and/or DTaP vaccine at the same time might be slightly more likely to have a seizure caused by fever.  Ask your doctor if a child who is getting flu vaccine has ever had a seizure. 

Problems that could happen after any injected vaccine:

  • People sometimes faint after a medical procedure, including vaccination.  Sitting or lying down for about 15 minutes can help prevent fainting, and injuries caused by fall.  Tell your doctor if you feel dizzy, or have vision changes or ringing in the ears.
  • Some people get severe pain in the shoulder and have difficulty moving the arm where a shot was given.  This happens rarely.
  • Any medication can cause a severe allergic reaction.  Such reactions from a vaccine are very rare, estimated at about 1 in a million doses, and would happen within a few minutes to a few hours after the vaccination. 
As with any medicine, there is a very remote chance of a vaccine causing a serious injury or death.

The safety of vaccines is always being monitored. For more information, visit:

 What if there is a serious reaction?

What should I look for?

  • Look for anything that concerns you, such as signs of a severe allergic reaction, very high fever, or unusual behavior. 
Signs of a severe allergic reaction can include hives, swelling of the face and throat, difficulty breathing, a fast heartbeat, dizziness, and weakness.  These would start a few minutes to a few hours after the vaccination.

What should I do?

  • If you think it is a severe allergic reaction or other emergency that can't wait, call 9-1-1 and get the person to the nearest hospital.  Otherwise, call your doctor. 
  • Reactions should be reported to the Vaccine Adverse Event Reporting System (VAERS).  Your doctor should file this report, or you can do it yourself through the VAERS web site at, or by calling 1-800-822-7967.
VAERS does not give medical advice.

 The National Vaccine Injury Compensation Program

The National Vaccine Injury Compensation Program (VICP) is a federal program that was created to compensate people who may have been injured by certain vaccines.

Persons who believe they may have been injured by a vaccine can learn about the program and about ling a claim by calling 1-800-338-2382 or visiting the VICP website at There is a time limit to le a claim for compensation.

 How can I learn more?

  • Ask your healthcare provider.  He or she can give you the vaccine package insert or suggest other sources of information. 
  • Call your local or state health department. 
  • Contact the Centers for Disease Control and Prevention (CDC):Call 1-800-232-4636 (1-800-CDC-INFO) or visit CDC's website at



Influenza Parent Information Guide 

If Your Child Is Sick

What can I do if my child gets sick?

Talk to your doctor early if you are worried about your child’s illness.

Make sure your child gets plenty of rest and drinks enough fluids. If your child is 5 years and older without long-term health problems and gets flu symptoms, including a fever and/or cough, consult your doctor as needed.

Children younger than 5 years – especially those younger than 2 years – and children with certain long-term health problems (including asthma, diabetes and disorders of the brain or nervous system), are at high risk of serious flu complications. Call your doctor or take your child to the doctor right away if they develop flu symptoms.

What if my child seems very sick?Even healthy children can get very sick from flu. If your child is experiencing the following emergency warning signs you should go to the emergency room:

Emergency warning signs of flu:

  •   Fast breathing or trouble breathing
  •   Bluish or gray skin color
  •   Not drinking enough fluids (not going to the bathroom or not making as much urine as they  normally do)
  •   Severe or persistent vomiting
  •   Not waking up or not interacting
  •   Being so irritable that the child does not want to be held
  •   Flu symptoms improve, but then return with fever and worse cough
  •   Fever with rash


Please read the Influenza Parent Information Guides below for more information.