Inactivated Influenza Vaccine

Why Get Vaccinated?

Influenza ("flu") is a contagious disease. It is caused by the influenza virus, which can be spread by coughing, sneezing, or nasal secretions. Anyone can get influenza, but rates of infection are highest among children. For most people, symptoms last only a few days. They include:

  • Fever
  • Sore throat
  • Chills
  • Fatigue
  • Cough
  • Headache
  • Muscle aches

Other illnesses can have the same symptoms and are often mistaken for influenza. Infants, the elderly, pregnant women, and people with certain health conditions - such as heart, lung or kidney disease or a weakened immune system - can get much sicker. Flu can cause high fever and pneumonia, and make existing medical conditions worse. It can cause diarrhea and seizures in children. Each year thousands of people die from seasonal influenza and even more require hospitalization.

By getting vaccinated you can protect yourself from influenza and may also avoid spreading influenza to others.

Inactivated Influenza Vaccine

There are two types of infl uenza vaccine:

  1. Inactivated (killed) vaccine, or the "flu shot" is given by injection into the muscle.
  2. Live, attenuated (weakened) influenza vaccine is sprayed into the nostrils.

A "high-dose" inactivated influenza vaccine is available for people 65 years of age and older. Ask your healthcare provider for more information.

Influenza viruses are always changing, so annual vaccination is recommended. Each year scientists try to match the viruses in the vaccine to those most likely to cause flu that year.

The 2010-2011 vaccine provides protection against A/H1N1 (pandemic) influenza and two other influenza viruses - influenza A/H3N2 and influenza B. It will not prevent illness caused by other viruses.

It takes up to 2 weeks for protection to develop after the shot. Protection lasts about a year.

Some inactivated influenza vaccine contains a preservative called thimerosal. Thimerosal-free influenza vaccine is available. Ask your healthcare provider for more information.

Who Should Get Inactivated Influenza Vaccine and When?


All people 6 months of age and older should get flu vaccine.

Vaccination is especially important for people at higher risk of severe influenza and their close contacts, including healthcare personnel and close contacts of children younger than 6 months.

People who got the 2009 H1N1 (pandemic) influenza vaccine, or had pandemic fl u in 2009, should still get the 2010-2011 seasonal infl uenza vaccine.


Getting the vaccine as soon as it is available will provide protection if the flu season comes early. You can get the vaccine as long as illness is occurring in your community.

Influenza can occur at any time, but most infl uenza occurs from November through May. In recent seasons, most infections have occurred in January and February. Getting vaccinated in December, or even later, will still be beneficial in most years.

Adults and older children need one dose of influenza vaccine each year. But some children younger than 9 years of age need two doses to be protected. Ask your healthcare provider.

Influenza vaccine may be given at the same time as other vaccines, including pneumococcal vaccine.

Some People Should Not Get Inactivated Influenza Vaccine or Should Wait

Tell your healthcare provider if you have any severe (life-threatening) allergies. Allergic reactions to influenza vaccine are rare.

Influenza vaccine virus is grown in eggs. People with a severe egg allergy should not get infl uenza vaccine.

A severe allergy to any vaccine component is also a reason not to get the vaccine.

If you ever had a severe reaction after a dose of influenza vaccine, tell your healthcare provider.

Tell your healthcare provider if you ever had Guillain- Barré Syndrome (a severe paralytic illness, also called GBS). Your provider will help you decide whether the vaccine is recommended for you.

People who are moderately or severely ill should usually wait until they recover before getting flu vaccine. If you are ill, talk to your healthcare provider about whether to reschedule the vaccination. People with a mild illness can usually get the vaccine.

What Are the Risks From Inactivated Influenza Vaccine?

A vaccine, like any medicine, could possibly cause serious problems, such as severe allergic reactions. The risk of a vaccine causing serious harm, or death, is extremely small.

Serious problems from inactivated influenza vaccine are very rare. The viruses in inactivated influenza vaccine have been killed, so you cannot get influenza from the vaccine.

Mild problems:

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

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

Severe problems:

  • Life-threatening allergic reactions from vaccines are very rare. If they do occur, it is usually within a few minutes to a few hours after the shot.
  • In 1976, a type of inactivated infl uenza (swine flu) vaccine was associated with Guillain-Barré Syndrome (GBS). Since then, flu vaccines have not been clearly linked to GBS. However, if there is a risk of GBS from current flu vaccines, it would be no more than 1 or 2 cases per million people vaccinated. This is much lower than the risk of severe influenza, which can be prevented by vaccination.

One brand of inactivated flu vaccine, called Afluria, should not be given to children 8 years of age or younger, except in special circumstances. A related vaccine was associated with fevers and fever-related seizures in young children in Australia. Ask your healthcare provider for more information.

What If There is a Severe Reaction?

What should I look for?

Any unusual condition, such as a high fever or behavior changes. Signs of a severe allergic reaction can include difficulty breathing, hoarseness or wheezing, hives, paleness, weakness, a fast heart beat or dizziness.

What should I do?

  • Call a doctor, or get the person to a doctor right away.
  • Tell the doctor what happened, the date and time it happened, and when the vaccination was given.
  • Ask your healthcare provider to report the reaction by filing a Vaccine Adverse Event Reporting System (VAERS) form.

The National Vaccine Injury Compensation Program

The National Vaccine Injury Compensation Program (VICP) was created in 1986. People who believe they may have been injured by a vaccine can learn about the program and about filling a claim by calling 1-800-338-2382.

How Can I Learn More?

Ask your healthcare provider. They 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): 1-800-232-4636 (1-800-CDC-INFO)

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