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Recombinant Influenza (Flu) Vaccine

Questions & Answers

What is Recombinant Flu Vaccine?

Recombinant flu vaccines is produced using a method does not require an egg-grown vaccine virus and does not use chicken eggs in the production process. Currently, recombinant flu vaccine is the only egg-free vaccine on the U.S. market.

Flublok Quadrivalent is a quadrivalent recombinant influenza vaccine that has been licensed by the FDA for use in adults 18 years and older.

How does Recombinant flu vaccine differ from the other approved flu vaccines?

Recombinant vaccine is produced differently and have a slightly shorter shelf life than most flu vaccines.

  • Recombinant flu vaccine does not use the influenza virus or chicken eggs in its manufacturing process. See How Influenza (Flu) Vaccines Are Made for more information.
  • Recombinant flu vaccine has a slightly shorter shelf life than most other currently available injectable influenza vaccines. It expires 9 months from the production date. Health care providers should check the expiration date before administering recombinant flu vaccine.

Who can get Flublok Quadrivalent?

Flublok Quadrivalent is approved for use in people 18 years and older.

Who should not get Flublok Quadrivalent?

People who are not within the FDA-approved age range (those younger than 18 years) and people with known severe allergic reactions to any component of the vaccine should not get Flublok Quadrivalent.

What are the possible benefits of recombinant flu vaccines?

The recombinant flu vaccine manufacturing process has the potential for faster startup, which can be useful in the event of a pandemic or vaccine supply shortage, mainly because it is not dependent on an egg supply or limited by the selection of vaccine viruses that are adapted for growth in eggs. Learn more about the recombinant flu vaccine manufacturing process on CDC’s How Flu Vaccines are Made web page.

Is this vaccine safe?

Clinical studies show that Flublok Quadrivalent is safe and effective for use in people 18 years and older. Flublok meets FDA’s standards for influenza vaccines.

Are there any side effects that could occur?

The most common side effects reported after receipt of Flublok Quadrivalent were similar to those reported for other flu shots and include pain at the injection site, headache, fatigue, and muscle aches.

For more information see the Flublok package insert.

Special Consideration Regarding Egg Allergy

People with egg allergies can receive any licensed, recommended age-appropriate influenza vaccine (IIV, RIV4, or LAIV4) that is otherwise appropriate. People who have a history of severe egg allergy (those who have had any symptom other than hives after exposure to egg) should be vaccinated in a medical setting, supervised by a health care provider who is able to recognize and manage severe allergic reactions.

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