Recombinant Influenza (Flu) Vaccine

Note: “Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices — United States, 2019–20 Influenza Season” has been published. CDC recommends annual influenza vaccination for everyone 6 months and older with any licensed, influenza vaccine that is appropriate for the recipient’s age and health status, (IIV, RIV4, or LAIV4) with no preference expressed for any one vaccine over another. Content on this website is being updated to reflect this most recent guidance. More information about the upcoming 2019-2020 flu season is available.

What is Recombinant Flu Vaccine?

Recombinant influenza vaccines are produced using recombinant technology. This method does not require an egg-grown vaccine virus and does not use chicken eggs in the production process. Currently, the recombinant influenza vaccine and the cell culture-based influenza vaccine are the only egg-free influenza vaccines licensed for use in the United States.

Flublok Quadrivalent is a quadrivalent recombinant influenza vaccine that was first licensed by the FDA in the United States for use in adults 18 years and older in 2017.  An earlier trivalent version was licensed in 2013, but has been replaced by the quadrivalent version.

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

Recombinant vaccines are produced differently from other vaccines.  Recombinant influenza vaccines do not use the influenza virus or chicken eggs in the manufacturing process. See How Influenza (Flu) Vaccines Are Made for more information.

Who can get Flublok Quadrivalent?

Flublok Quadrivalent is licensed for use in people 18 years of age 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?

Because it is not dependent on an egg supply, the recombinant influenza vaccine manufacturing process might be faster than that of egg-based vaccines in the event of a pandemic or shortage of the eggs needed to grow influenza viruses, and is not limited by the selection of vaccine viruses that are adapted for growth in eggs.  This process also avoids mutations that can occur when viruses are grown in eggs, which can sometimes affect how well the finished vaccine works.  Learn more about the recombinant influenza vaccine manufacturing process on CDC’s How Flu Vaccines are Made web page.

Is this vaccine safe? Are there any side effects that could occur?

In clinical studies, the safety of recombinant influenza vaccines was comparable to that of other injectable influenza vaccines.  The most common side effects reported after receipt of Flublok Quadrivalent were similar to those reported for other injectable vaccines and include pain and tenderness at the injection site, headache, fatigue, and muscle or joint aches.

For more information see the Flublok Quadrivalent package insertexternal icon.

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 and supervised by a health care provider who is able to recognize and manage severe allergic reactions.