The US Food and Drug Administration (FDA) has approved Fluad, the first seasonal influenza vaccine containing an adjuvant. Fluad, a trivalent vaccine produced from three influenza virus strains (two subtype A and one type B), is approved for the prevention of seasonal influenza in people 65 years of age and older.

Fluad, which is manufactured using an egg-based process, is formulated with the adjuvant MF59, 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. Adjuvants are incorporated into some vaccine formulations to enhance or direct the immune response of the vaccinated individual.

According to the Centers for Disease Control and Prevention, in recent years, it is estimated that 80 to 90 per cent of seasonal influenza-related deaths and 50 to 70 per cent of seasonal influenza-related hospitalisations have occurred among people 65 years of age and older.

“Fluad provides another alternative for a safe and effective influenza vaccine in people 65 years of age and older,” said Karen Midthun, M.D., director of the FDA’s Center for Biologics Evaluation and Research.

“Immunising individuals in this age group is especially important because they bear the greatest burden of severe influenza disease and account for the majority of influenza-related hospitalisations and deaths.”

Fluad was evaluated in a multicenter clinical trial conducted in the United States and internationally that compared the safety and immunogenicity (ability to generate an antibody response) of Fluad to Agriflu, an FDA-approved unadjuvanted trivalent seasonal influenza vaccine, in individuals 65 years of age and older. In that trial, 7,082 participants received either Fluad or Agriflu. The study showed that Fluad induced antibody levels that were comparable to the levels induced by Agriflu.

Safety was also evaluated in approximately 27,000 additional individuals 65 years of age and older. No safety concerns were identified with Fluad. The most common adverse events reported include injection site pain and tenderness, muscle aches, headache and fatigue.

Fluad was approved using the accelerated approval regulatory pathway, which allows the FDA to approve products for serious or life-threatening diseases based on evidence that the product has an effect on an outcome that is reasonably likely to predict clinical benefit. In the case of Fluad, the antibody response to the vaccine provided this evidence. Under the accelerated approval requirements, a confirmatory study is required to verify and describe the clinical benefit of Fluad.

Fluad was first approved for use in Italy in 1997 and is currently approved in 38 countries, including Canada and 15 European countries. Fluad and Agriflu are manufactured by Novartis Vaccines and Diagnostics Limited, an affiliate of Novartis Vaccines and Diagnostics, Inc., based in Cambridge, Massachusetts.