H5N1 influenza is sometimes called avian flu or "bird flu" because it is usually found in birds, including domestic poultry such as chickens and geese. You cannot become infected with H5N1 influenza from eating fully cooked poultry products.

Influenza A subtype H5N1 is caused by a virus, and this virus affects mainly birds in Asia and Africa. Human infection with H5N1 influenza is rare, but you can become infected by having direct contact with sick or dead birds that have been infected with H5N1 influenza virus. You may also come into contact with H5N1 influenza virus if you visit a live poultry market.

Although H5N1 influenza virus is not easily transmitted from person to person, you can become infected if you have prolonged close contact with another person who has become infected with avian flu.

Influenza Virus Vaccine, H5N1 is used to help prevent disease in people who are at risk of coming into contact with infected birds or other sources of the virus.

Influenza Virus Vaccine, H5N1 is for use in adults and children who are at least 6 months old.

Influenza Virus Vaccine, H5N1 works by exposing you to a small dose of the virus, which causes the body to develop immunity to the disease. This vaccine will not treat an active infection that has already developed in the body.

Like any vaccine, the H5N1 influenza virus vaccine may not provide protection from disease in every person.

You should not receive a booster vaccine if you had a life threatening allergic reaction after the first shot.

H5N1 influenza virus vaccine is given as an injection (shot) into a muscle.

Influenza Virus Vaccine, H5N1 is given in a series of 2 shots. The booster shot is given 21 days after your first shot.

Your individual booster schedule may be different from these guidelines. Follow your doctor's instructions or the schedule recommended by the health department of the state you live in.

You may receive other vaccines at the same time you receive H5N1 influenza virus vaccine.

The H5N1 influenza virus vaccine is a "killed virus" vaccine and will not cause you to become ill with the flu virus that it contains. However, you may have flu-like symptoms at any time during flu season that may be caused by other strains of influenza virus.

Your should not receive Influenza Virus Vaccine, H5N1 if:

• you are allergic to eggs; or

• you have had a life-threatening allergic reaction to influenza vaccine or "flu shot."

Before receiving Influenza Virus Vaccine, H5N1, tell your doctor if you have ever received an influenza vaccine that caused Guillain Barré syndrome (within 6 weeks after receiving the vaccine).

If you have any of these other conditions, your vaccine may need to be postponed or not given at all:

• an allergy to eggs or chicken products;

• a weak immune system (caused by disease or by using certain medicine); or

• if someone in your household has a weak immune system.

You can still receive a vaccine if you have a minor cold. In the case of a more severe illness with a fever or any type of infection, wait until you get better before receiving Influenza Virus Vaccine, H5N1.

It is not known whether H5N1 influenza virus vaccine will harm an unborn baby. However, if you are at a high risk for infection with H5N1 influenza during pregnancy, your doctor should determine whether you need Influenza Virus Vaccine, H5N1.

Do not receive this vaccine without telling your doctor you are breast-feeding a baby.

Contact your doctor if you miss a booster dose or if you get behind schedule. The next dose should be given as soon as possible. There is no need to start over.

Be sure to receive all recommended doses of Influenza Virus Vaccine, H5N1 or you may not be fully protected against disease.

An overdose of Influenza Virus Vaccine, H5N1 is unlikely to occur.

Follow your doctor's instructions about any restrictions on food, beverages, or activity.

Get emergency medical help if you have signs of an allergic reaction tp Influenza Virus Vaccine, H5N1: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

You should not receive a booster vaccine if you had a life-threatening allergic reaction after the first shot.

Keep track of any and all side effects you have after receiving Influenza Virus Vaccine, H5N1. When you receive a booster dose, you will need to tell the doctor if the previous shot caused any side effects.

You may feel faint after receiving this vaccine. Some people have had seizure like reactions after receiving this vaccine. Your doctor may want you to remain under observation during the first 15 minutes after the injection.

Becoming infected with H5N1 influenza is much more dangerous to your health than receiving this vaccine. However, like any medicine, Influenza Virus Vaccine, H5N1 can cause side effects but the risk of serious side effects is extremely low.

Common Influenza Virus Vaccine side effects may include:

• pain or tenderness where the shot was given;

• muscle pain;

• fussiness, irritability, crying for an hour or longer;

• headache; or

• general ill feeling.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report vaccine side effects to the US Department of Health and Human Services at 1-800-822-7967.

Also tell the doctor if you have recently received drugs or treatments that can weaken the immune system, including:

• an oral, nasal, inhaled, or injectable steroid medicine;

• chemotherapy or radiation cancer treatments;

• medications to treat psoriasis, rheumatoid arthritis, or other autoimmune disorders; or

• medicines to treat or prevent organ transplant rejection.

If you are using any of these medications, you may not be able to receive the vaccine, or may need to wait until the other treatments are finished.

This list is not complete. Other drugs may interact with H5N1 influenza virus vaccine, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.