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For the first time, an influenza vaccine containing an immune-boosting compound called an adjuvant has been cleared to enter the crowded US flu vaccine market.

The Food and Drug Administration announced Tuesday that it has approved Fluad for people 65 and older.

As people age, their immune systems wane and vaccines don’t generate as much protection for them. Adding an adjuvant helps to trigger a stronger immune response.


The compounds can also be used at times of vaccine shortage to stretch out supplies by allowing less vaccine to be used for each person. Several countries used adjuvanted vaccines during the 2009 H1N1 flu pandemic; the United States was not among them.

Fluad protects against three strains of flu — the influenza A viruses H3N2 and H1N1, and one family of influenza B viruses. Some seasonal flu vaccines protect against four strains — two As and two Bs.


Fluad has been used in Europe for more than a decade. First approved in Italy in 1997, it is now sold in 38 countries, including Canada. While it is the first flu vaccine on the US market to include an adjuvant, it isn’t the only one using a special formulation to try to increase protection for seniors. Sanofi Pasteur sells a high-dose flu vaccine called Fluzone High-Dose, which contains four times as much vaccine per shot as regular vaccines.

Infectious diseases expert Michael Osterholm said the approval gives seniors another option to help them avoid the flu. “It’s an incremental step in a positive way toward improving flu vaccine protection,” he said. Osterholm, director of the Center for Infectious Diseases Research and Policy at the University of Minnesota, has long advocated for “game-changing” influenza vaccines, ones that would be much more effective than the current generation.

The FDA said the approval was based on a clinical trial in which Fluad elicited a stronger immune response against most of the influenza strains than a comparable non-adjuvanted vaccine. The study included more than 7,000 elderly participants.

Fluad was created by a division of the Swiss drug giant Novartis, which sold the product to the Australian vaccine maker CSL in August. Earlier this month, CSL announced it was changing its name to Seqirus.

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