Recombinant Influenza (Flu) Vaccine
Recombinant influenza (flu) 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.
Recombinant flu vaccine was first licensed by the FDA in the United States in 2013. Currently, the recombinant flu vaccine and the cell culture-based flu vaccine are the only egg-free flu vaccines licensed for use in the United States.
There is one quadrivalent recombinant flu shot (Flublok Quadrivalent) available for the 2022–2023 influenza season.
Recombinant flu vaccines do not use the flu virus or chicken eggs in the manufacturing process. More information is available at How Influenza (Flu) Vaccines Are Made.
Flublok Quadrivalent is licensed for use in people 18 years and older.
People who are not within the FDA-approved age range (those younger than 18 years) and who have had severe allergic reactions to any ingredient of the vaccine should not get Flublok Quadrivalent.
Recombinant flu vaccine (brand name: Flublok Quadrivalent) is one of the three vaccines that are preferentially recommended for people 65 years and older because a review of existing studies suggested that, in this age group, these vaccines are potentially more effective than standard dose unadjuvanted flu vaccines. Other possible benefits of recombinant vaccine include that this vaccine technology is not dependent on an egg supply so the 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. This process is not limited by the selection of vaccine viruses that are adapted for growth in eggs. It 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 flu vaccine manufacturing process on CDC’s How Flu Vaccines are Made.
- What is Recombinant Flu Vaccine?
- How does Recombinant flu vaccine differ from the other approved flu vaccines?
- Who can get Flublok Quadrivalent?
- Who should not get Flublok Quadrivalent?
- What are the possible benefits of recombinant flu vaccines?
- Is this vaccine safe? Are there any side effects that could occur?
- Special Consideration Regarding Egg Allergy
Recombinant flu vaccines production does not require an egg-grown vaccine virus and does not use chicken eggs at all in the production process.
Are any of the available flu vaccines recommended over others?
Yes, for some people. For the 2022-2023 flu season, there are three flu vaccines that are preferentially recommended for people 65 years and older. These are Fluzone High-Dose Quadrivalent vaccine, Flublok Quadrivalent recombinant flu vaccine and Fluad Quadrivalent adjuvanted flu vaccine. This recommendation was based on a review of available studies which suggests that, in this age group, these vaccines are potentially more effective than standard dose unadjuvanted flu vaccines. There is no preferential recommendation for people younger than 65 years.
What if a preferentially recommended flu vaccine is not available?
If none of the three flu vaccines preferentially recommended for people 65 years and older is available at the time of administration, people in this age group should get any other age-appropriate flu vaccine instead.
In clinical studies, the safety of recombinant flu vaccines was comparable to that of other injectable flu 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 insert.
People with egg allergies can receive any licensed, recommended age-appropriate influenza (flu) vaccine (IIV4, 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.