Adjuvanted Flu Vaccine

This page provides information on FLUAD and FLUAD Quadrivalent influenza vaccines. More information about FLUAD external iconand FLUAD Quadrivalentexternal icon are available on the Food and Drug Administration (FDA) web site.

What is FLUAD?

FLUAD and FLUAD Quadrivalent is a standard-dose, inactivated influenza (flu) vaccine, manufactured by Seqirus that contains an adjuvant. During the 2020-2021 influenza season, both trivalent FLUAD and FLUAD Quadrivalent will be available. Both of these vaccines are approved for people 65 years and older. They are manufactured using an egg-based process (like most flu vaccines), and are formulated with an adjuvant called MF59. An adjuvant is an ingredient added to a vaccine that helps create a stronger immune response to vaccination.

What is MF59?

MF59 is an oil-in-water emulsion of squalene oil. Squalene, a naturally occurring substance found in humans, animals and plants, is highly purified for the vaccine manufacturing process. FLUAD is approved for use among people 65 years and older, who often have a lower protective immune response after flu vaccination compared to younger, healthier people.

Why are adjuvants added to flu vaccines?

An adjuvant is an ingredient of a vaccine that helps promote a better immune response. Adjuvants also can reduce the amount of virus needed for production of a vaccine, which can allow for greater supplies of vaccine to be manufactured.

Is FLUAD approved in other countries, besides the U.S.?

FLUAD was initially approved in Italy in 1997, and at the time of its U.S. approval in November 2015, had been licensed in 38 countries, including Canada and 15 European countries. FLUAD Quadrivalent was approved in the United States in 2020; it will be available for the first time during the 2020-21 season.

Who can receive FLUAD and FLUAD Quadrivalent?

In the United States, FLUAD and FLUAD Quadrivalent are licensed only for persons aged 65 years and older. FLUAD and FLUAD Quadrivalent should not be given to people with a history of severe allergic reaction to the any flu vaccine or to vaccine ingredients other than eggs. Information about vaccine ingredients is located in package inserts from each manufacturer.

Are there benefits of FLUAD and FLUAD Quadrivalent compared to standard-dose flu vaccines without adjuvant for adults 65 years and older?

Studies that have tested trivalent FLUAD’s ability to generate an immune response against flu viruses (immunogenicity) have found that antibody levels were comparable to levels induced by a standard-dose, egg-based vaccine without adjuvant. A recent study published in the Journal of Infectious Diseases among Medicare beneficiaries 65 years and older found that trivalent FLUAD provided greater protection against flu-related hospitalizations than standard-dose, egg-based flu vaccine.

Data comparing the effectiveness of FLUAD Quadrivalent with standard-dose unadjuvanted inactivated vaccines are not yet available.

Does FLUAD and FLUAD Quadrivalent offer better protection than the high-dose flu vaccine?

To date, there have been no randomized studies comparing FLUAD and FLUAD Quadrivalent with High-Dose flu vaccine (brand name, Fluzone High-Dose and Fluzone High-Dose Quadrivalent) against laboratory-confirmed influenza.

If you have questions about which vaccine is best for you, talk to your doctor or other health care professional.

Does CDC recommend one vaccine above another for people 65 years and older?

People 65 years and older can get any flu vaccine approved for use in that age group with no preference for any one vaccine over another. CDC recommends flu vaccination as the first and most important step in protecting against flu.

How safe are FLUAD and FLUAD Quadrivalent?

Some adverse events (which are also reported after regular flu vaccines) were reported more frequently after vaccination with trivalent FLUAD. The most common adverse events experienced during clinical studies were mild to moderate and were temporary, and included pain, redness at the injection site, headache, muscle aches, and malaise. In a study comparing FLUAD Quadrivalent with trivalent FLUAD, some of these side effects were slightly more common with the quadrivalent vaccine, but most were mild and resolved within a few days.

Where can I find more information about FLUAD?

More information about FLUADexternal icon and FLUAD Quadrivalentexternal icon is available on the Food and Drug Administration (FDA) web site.

What other flu vaccines are available for people 65 years and older?

In addition to FLUAD and FLUAD Quadrivalent, one other flu vaccine is licensed specifically for people 65 years and older. The high-dose flu vaccine (Fluzone High-Dose Quadrivalent) contains four times the amount of antigen as the standard-dose inactivated flu vaccine, and has been associated with a stronger immune response following vaccination and better effectiveness than the regular dose flu vaccine in older people in a two-season randomized trial. People in this age group may also receive standard-dose, flu vaccines without adjuvant or the recombinant flu vaccine. People 65 years and older can get any flu vaccine approved for use in that age group with no preference for any one vaccine over another.

Why is there a need for flu vaccines designed specifically for people 65 years and older?

People 65 years and older are at the highest risk for flu-related deaths and they have poorer immune responses to flu vaccines than younger people. CDC studies conducted during previous flu seasons estimateexternal icon that people 65 years and older account for 70 to 85 percent of flu-related deaths and 50 to 70 percent of flu-related hospitalizations each flu season. Older adults typically show lower protective immune responses after flu vaccination compared to healthy young people. Lower immune responses may lead to lower vaccine effectiveness (i.e., a measure of how well the flu vaccine protects against flu illness). Given the high risk of severe flu illness and low protective immune response after vaccination among older adults, substantial research and development have produced new influenza vaccines intended to provide better immunity in this age group.