General Information

Fluad is a trivalent vaccine produced from three influenza virus strains (two subtype A and one type B). Fluad Quad is a quadrivalent vaccine and utilizes the same MF59 adjuvant technology as Fluad, but includes an additional strain.

Fluad/Fluad Quad is specifically indicated for the prevention of seasonal influenza in people 65 years of age and older.

Fluad is supplied as a solution for intramuscular injection. The recommended dose is a single 0.5 mL dose.

Mechanism of Action

Influenza illness and its complications follow infection with influenza viruses. Global surveillance of influenza identifies yearly antigenic variants. Specific levels of hemagglutination inhibition (HI) antibody titers induced by vaccination with inactivated influenza virus vaccine have not been correlated with protection from influenza illness. Antibody against one influenza virus type or subtype confers limited or no protection against another. Furthermore, antibody to one antigenic variant of influenza virus might not protect against a new antigenic variant of the same type or subtype. Frequent development of antigenic variants through antigenic drift is the virologic basis for seasonal epidemics and the reason for the usual change of one or more new strains in each year's influenza vaccine. Therefore, inactivated trivalent/quadrivalent influenza vaccines are standardized to contain the hemagglutinin of influenza virus strains (two subtypes A and one type B), representing the influenza viruses likely to be circulating in the United States in the upcoming influenza season.

Side Effects

Adverse effects associated with the use of Fluad may include, but are not limited to, the following:

local (injection site) adverse reactions:

• injection site pain
• tenderness

systemic adverse reactions

• myalgia
• headache
• fatigue

Clinical Trial Results

The FDA approval of Fluad was based on a safety and immunogenicity study of Fluad in comparison to Agriflu. A total of 7,082 subjects were randomized and vaccinated with Fluad or Agriflu. The primary immunogenicity analyses were conducted on all vaccinated subjects with a blood sample collected at Day 22. Non-inferiority of Fluad compared with Agriflu was demonstrated for all three vaccine strains based on pre-defined thresholds for seroconversion rate differences and GMT ratios.