Cell-Based Flu Vaccines

Brand name: Flucelvax Quadrivalent

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 are cell-based flu vaccines?

‘Cell-based’ refers to how the flu vaccine is made. Most inactivated influenza vaccines are produced by growing influenza viruses in eggs. The influenza viruses used in the cell-based vaccine are grown in cultured cells of mammalian origin instead of in hens’ eggs.

Flucelvax Quadrivalent is the only cell-based inactivated influenza vaccine that has been licensed by the FDA for use during the 2019-2020 flu season.

Who can get Flucelvax Quadrivalent?

Flucelvax Quadrivalent is licensed for use in people 4 years and older.

Why has a cell-based flu vaccine been developed?

A cell-based flu vaccine was developed as an alternative to the egg-based manufacturing process. Cell-culture technology is potentially more flexible than the traditional technology, which relies upon adequate supply of eggs. In addition, the cell-based flu vaccine that uses cell-based candidate vaccine viruses (CVVs) has the potential to offer better protection than traditional, egg-based flu vaccines as a result of being more similar to flu viruses in circulation.

While viruses used in Flucelvax Quadrivalent have been grown in cells since the vaccine first became available, prior to the 2019-2020 season some of the viruses provided to the manufacturer had been originally derived in eggs. For the 2019-2020 influenza season, all four flu viruses used in the Flucelvax Quadrivalent are cell-derived, making the vaccine egg-free.

How is the cell-based vaccine manufacturing process different than the traditional egg-based manufacturing process?

In place of fertilized chicken eggs, the cell-based vaccine manufacturing process uses animal cells (Madin-Darby Canine Kidney, or MDCK cells) in liquid culture as a host for the growing influenza virus. For the 2019-20 season, the viruses provided to the manufacturer to be grown in cell culture are cell-derived rather than egg derived. Learn more about the cell-based flu vaccine manufacturing process on CDC’s How Flu Vaccines are Made web page.

What is the significance of FDA approving cell-based candidate vaccine viruses for use in the Flucelvax Quadrivalent cell-based flu vaccines?

Growing influenza viruses in eggs can introduce changes (called egg-adapted changes) that can cause differences between the viruses in the vaccine and the ones that are circulating. These changes can have important implications for the body’s immune response to vaccination. For example, these egg-adapted changes could cause the body’s immune system to produce antibodies that are less effective at preventing disease caused by the specific flu viruses in circulation. FDA approval of cell-grown CVVs will reduce egg-adapted changes and may result in vaccines containing virus that is more “like” wild-type circulating viruses. Therefore, the FDA’s approval of cell-based candidate vaccine viruses has the potential to improve the effectiveness of cell-based flu vaccines.

What are the possible benefits of using cell-based influenza vaccines?

A potential advantage of cell culture technology is that it might permit faster start-up of the vaccine manufacturing process in the event of a pandemic. The cells used to manufacture Flucelvax Quadrivalent are kept frozen and “banked.” Cell banking assures an adequate supply of cells is readily available for vaccine production. Growing the influenza viruses in cell culture for the manufacture of Flucelvax Quadrivalent is not dependent on an egg supply. Also, as described above, cell-based flu vaccines that are produced using cell-based candidate vaccine viruses have the potential to improve the effectiveness of cell-based flu vaccines (compared to egg-based flu vaccines) by eliminating the kinds of egg adaptations that occur in egg-manufactured flu vaccines.

What were the results of the clinical trials using cell-based technology?

A clinical trial of the previous trivalent formulation of Flucelvax demonstrated effectiveness and safety among persons 18 through 49 years of age. In immunogenicity studies among people 18 years if age and older and 4 through 17 years of age, Flucelvax Quadrivalent was found to produce a similar immune response to the trivalent formulation. Post-vaccination symptoms were typical of those seen with other injectable influenza vaccines.

Has cell-based technology been used before?

Cell culture technology has been used to produce other U.S.-licensed vaccines, including vaccines for rotavirus, polio, smallpox, hepatitis, rubella and chickenpox.

Cell-based flu vaccines have been approved for use in multiple European countries.