The Food and Drug Administration (FDA) has approved a quadrivalent formulation of Flublok influenza vaccine (Protein Sciences). Flublok Quadrivalent contains the three strains found in trivalent Flublok plus an additional B strain.  

Compared to other quadrivalent influenza vaccines, Flublok Quadrivalent contains three times more active ingredient, making it the first high antigen quadrivalent vaccine approved by the FDA.

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In a clinical study of 9,000 adults 50 years of age and older, people who received Flublok Quadrivalent were over 40% less likely to get cell-culture confirmed influenza than those that received a leading egg-produced quadrivalent flu vaccine. 

Flublock Quadrivalent is indicated for active immunization against disease caused by influenza A virus subtypes and influenza B virus contained in the vaccine.  It is approved for patients 18 years of age and older.

Just like the trivalent formulation, Flublok Quadrivalent is a recombinant protein-based vaccine that contains no egg proteins, antibiotics, or preservatives.

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