Clinical Efficacy Study of Flublok® Quadrivalent Compares Flublok to a Traditional Egg-based Flu Vaccine

Jan 29, 2015, 10:06 ET from Protein Sciences Corporation

MERIDEN, Conn., Jan. 29, 2015 /PRNewswire/ -- Protein Sciences Corporation announced today that results from a double-blinded comparative efficacy study of Flublok Quadrivalent in adults over 50 are expected in June. The study is designed to demonstrate whether Flublok's higher antigen content and its modern production process that avoids the introduction of egg-based mutations into the vaccine's active ingredients will result in better efficacy than the recently announced flu vaccine efficacy of 14% in adults older than 50.    

PSC12 is a large trial in adults 50 years of age and older intended to demonstrate the protective efficacy of Flublok Quadrivalent in prevention of influenza disease. The trial enrolled 9,000 participants at sites across the U.S. The efficacy of Flublok Quadrivalent is being compared to that of a licensed conventional egg-based inactivated quadrivalent vaccine.

Flublok Quadrivalent is a quadrivalent version of Flublok influenza vaccine that is designed to protect against two A subtypes and two B lineages of influenza.  Trivalent Flublok that protects against two A subtypes and one B lineage of influenza is licensed by the FDA for all adults 18 and older and is available for general use.  Flublok has gained popularity due to its purity, egg-free nature and high antigen content and is considered especially important in a flu season such as this that is severe due to the predominance and drift in the H3N2 virus.  The recombinant technology used to make Flublok is able to perfectly match circulating flu strains and, therefore, may prove more effective than traditional vaccines.  Clinical trials have suggested that the higher antigen content of Flublok provides significant protection against drifted influenza viruses.

A separate Phase 3 clinical trial of Flublok Quadrivalent is being conducted in adults 18-49 years of age.  PSC16 is intended to demonstrate that satisfactory immune responses are elicited for all four influenza proteins by Flublok Quadrivalent. The trial enrolled 1,350 adults across the U.S. and will compare Flublok Quadrivalent to a licensed conventional egg-based inactivated quadrivalent vaccine.  Results are also expected in June.

"There has been a shift in influenza vaccines to quadrivalent formulations," commented Manon Cox, President and CEO of Protein Sciences. "Our recombinant platform technology that we use to make Flublok and all other vaccines allows us to rapidly and predictably manufacture antigens that are perfectly matched to circulating influenza strains, whether it be the addition of a fourth antigen as in the case of Flublok Quadrivalent, or to update the annual formulation of Trivalent Flublok.  PSC12 and PSC16 put us on track for receiving regulatory approval of Flublok Quadrivalent in the next year or two." 

Trivalent Flublok is available now.  Healthcare professionals seeking the vaccine should contact FFF Enterprises at 800-843-7477 or online at  Consumers seeking Flublok should visit

About Protein Sciences

Protein Sciences specializes in vaccine development and protein production.   Our mission is our inspiration: to save lives and improve health through the creation of innovative vaccines and biopharmaceuticals.     

Flublok, the world's first recombinant protein-based vaccine for the prevention of seasonal influenza disease, was approved by FDA in January 2013.  Flublok is the only flu vaccine made in a 100% egg-free system using modern cell culture technology, making it unnecessary to use an infectious influenza virus or antibiotics in manufacturing.  Flublok is highly purified and does not contain any preservatives (e.g., thimerosal, a mercury derivative), egg proteins, gelatin or latex.  In addition, Flublok contains three times more antigen than traditional flu vaccines (3x45mcg hemagglutinin protein versus 3x15mcg hemagglutinin protein)*.   Flublok is a perfect copy of the virus coat and is not subject to the egg-adapted mutations associated with low vaccine effectiveness (see Skowronski et al. (2014) PLOS ONE 9(3), e92153).

Healthcare professionals can order Flublok by contacting FFF Enterprises at 800-843-7477.

Learn more at and

Flublok Safety Information

Flublok is approved for people 18 and older to prevent influenza disease.  The most common side effect from Flublok is pain at the site of injection. Headache, fatigue or muscle ache may occur.

Tell the doctor if you have ever experienced Guillain-Barre syndrome (severe muscle weakness) or have had a severe allergic reaction to any component of Flublok vaccine.

Vaccination with Flublok may not protect all individuals. Clinical effectiveness in adults 50 and older is based on the immune response elicited by Flublok and not on demonstration of decreased influenza disease. 

Please see the complete Package Insert available at or call 203-686-0800 for more information.

*Flublok demonstrated a higher antibody response to the A strains during 2 clinical trials in adults ≥50 years old.  The B strain antibody response was comparable to traditional trivalent vaccines.

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SOURCE Protein Sciences Corporation