Skip to Content

What is the difference between Flublok and Flublok Quadrivalent?

Medically reviewed by Last updated on Oct 7, 2019.

Official Answer


Flublok is a trivalent influenza vaccine, whereas Flublok Quadrivalent protects against four influenza strains instead of just three, and is the first high antigen content quadrivalent vaccine with triple the active ingredient.

Flublok (influenza vaccine, recombinant hemagglutinin) was originally approved for immunization against seasonal influenza in adults 18 years of age and older. The FDA has also approved a quadrivalent formulation of Flublok for adults, too.

High antigen content flu vaccines may offer an advantage to people at high risk, such as seniors or those with lowered immunity. Flublok Quadrivalent has the same purity advantages as trivalent Flublok, containing pure protein made without infectious influenza virus, antibiotics, eggs, thimerosal, preservatives, gelatin or latex. See also:

Related Medical Questions

Drug Information

Related Support Groups