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Influenza virus vaccine (injection)

Generic name: influenza virus vaccine (injection) (IN floo EN za VYE rus VAK seen)
Brand name: Afluria PF Pediatric Quadrivalent 2021-2022, Afluria PF Quadrivalent 2021-2022, Afluria Quadrivalent 2021-2022, Fluarix PF Quadrivalent 2021-2022, Flublok Quadrivalent 2021-2022, Flucelvax PF Quadrivalent 2021-2022, Flucelvax Quadrivalent 2021-2022, FluLaval PF Quadrivalent 2021-2022, Fluzone High-Dose Quadrivalent PF 2021-2022, Fluzone PF Pediatric Quadrivalent 2021-2022, Fluzone PF Quadrivalent 2021-2022, Fluzone Quadrivalent 2021-2022, all 199 brand names
Dosage forms: intramuscular solution (recombinant hemagglutinin quadrivalent); intramuscular suspension (adjuvanted preservative-free quadrivalent; high-dose preservative-free quadrivalent; mdck cell derived quadrivalent; preservative-free mdck cell derived quadrivalent; preservative-free pediatric quadrivalent; preservative-free quadrivalent; quadrivalent)
Drug class: Viral vaccines

Medically reviewed by on Oct 7, 2021. Written by Cerner Multum.

What is influenza virus vaccine?

Influenza virus ("the flu") is a contagious disease caused by a virus that can spread from one person to another through the air or on surfaces. Flu symptoms include fever, chills, tiredness, aches, sore throat, cough, vomiting, and diarrhea. The flu can also cause sinus infections, ear infections, bronchitis, or serious complications such as pneumonia.

Influenza causes thousands of deaths each year, and hundreds of thousands of hospitalizations. Influenza is most dangerous in children, pregnant women, older adults, and people with weak immune systems or health problems such as diabetes, heart disease, or cancer.

Influenza virus vaccine is for use in adults and children at least 6 months old, to prevent infection caused by influenza virus. This vaccine helps your body develop immunity to the disease, but will not treat an active infection you already have.

Influenza virus vaccine is redeveloped each year to contain specific strains of inactivated (killed) flu virus that are recommended by public health officials for that year.

The injectable influenza virus vaccine (flu shot) is made from "killed viruses." Influenza virus vaccine is also available in a nasal spray form, which is a "live virus" vaccine. This medication guide addresses only the injectable form of this vaccine.

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


Influenza virus vaccine is made from "killed viruses" and will not cause you to become ill with the flu virus.

Before taking this medicine

You may not be able to receive this vaccine if you are allergic to eggs, or if you have ever had a severe allergic reaction to a flu vaccine.

Tell your vaccination provider if you have:

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

  • a history of Guillain-Barre syndrome (within 6 weeks after receiving a flu vaccine).

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 this vaccine.

Tell your vaccination provider if you are pregnant or breastfeeding.

The Centers for Disease Control and Prevention recommends that pregnant women get a flu shot during any trimester of pregnancy to protect themselves and their newborn babies from flu. The nasal spray form of influenza vaccine is not recommended for use in pregnant women.

How is this vaccine given?

Some brands of this vaccine are made for use in adults and not in children. Your child's vaccination provider can recommend the best influenza virus vaccine for your child.

This vaccine is given as an injection (shot) into a muscle.

Children 6 months to 8 years old may need a second flu shot 4 weeks after receiving the first vaccine.

The influenza virus vaccine is usually given in October or November. Follow your doctor's instructions or the schedule recommended by your local health department.

Since the influenza virus vaccine is redeveloped each year for specific strains of influenza, you should receive a flu vaccine every year.

What happens if I miss a dose?

Call your doctor if you forget to receive your yearly flu shot in October or November, or if your child misses a booster dose.

What happens if I overdose?

An overdose of this vaccine is unlikely to occur.

What should I avoid before or after receiving this vaccine?

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

Influenza virus vaccine side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficulty 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. If you receive an influenza virus vaccine in the future, you will need to tell the vaccination provider if the previous shot caused any side effects.

Influenza virus vaccine is made from "killed viruses" and will not cause you to become ill with the flu virus. You may have flu-like symptoms at any time during flu season that may be caused by other strains of influenza virus.

Call your doctor at once if you have:

  • a light-headed feeling, like you might pass out;

  • severe weakness or unusual feeling in your arms and legs;

  • numbness, pain, tingling, burning or prickly feeling;

  • vision or hearing problems; or

  • a fever higher than 101 degrees F.

Common side effects may include:

  • pain, redness, tenderness, swelling, bruising, or a hard lump where the shot was given;

  • diarrhea, loss of appetite;

  • muscle pain;

  • headache, tiredness; or

  • fussiness, crying, or drowsiness in a child.

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.

Influenza virus vaccine dosing information

Usual Adult Dose for Influenza Prophylaxis:

0.5 mL, IM, once

Fluzone Intradermal(R):
0.1 mL, intradermally, once

Usual Pediatric Dose for Influenza Prophylaxis:

6 months to 35 months: 0.25 mL, IM - 1 or 2 doses; if 2 doses, administer 1 month apart
3 to 8 years old: 0.5 mL (1 dose), IM - 1 or 2 doses; if 2 doses, administer 1 month apart
9 years and older: 0.5 mL, IM, once

-Previously unvaccinated children (under 9 years of age) should receive 2 doses.
-Some previously vaccinated children should receive 2 doses: check current ACIP guidelines.
-Check the approved age range for the vaccine being used.
-The deltoid muscle of the upper arm is the preferred administration site.

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What other drugs will affect influenza virus vaccine?

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 affect influenza virus vaccine, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

Further information

  • Your vaccination provider, pharmacist, or doctor can provide more information about this vaccine. Additional information is available from your local health department or the Centers for Disease Control and Prevention.

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.