FDA Approves Flublok Quadrivalent Influenza Vaccine

Product contains B strain not found in trivalent Flublok

The FDA has given the green light to a quadrivalent formulation of Flublok influenza vaccine (Protein Sciences Corporation). Flublok Quadrivalent protects against four strains of influenza––three of the same strains found in trivalent Flublok plus an additional B strain.

Flublok Quadrivalent is the first and only high-antigen-content quadrivalent flu vaccine approved by the FDA, according to Protein Sciences. It contains three times more active ingredient than all other quadrivalent vaccines on the market.

In a clinical study of 9,000 adults 50 years of age and older, those who received Flublok Quadrivalent were more than 40% less likely to develop cell culture-confirmed influenza than were those who received a leading egg-produced quadrivalent flu vaccine. These results are also relevant for trivalent Flublok, the manufacturer says, since the H3N2 component of the vaccine that is shared between trivalent Flublok and Flublok Quadrivalent predominately contributed to the improved efficacy. 

Flublok Quadrivalent is approved for adults 18 years of age and older, and will be available in prefilled syringes beginning in 2017. The product contains pure protein made without infectious influenza virus, antibiotics, eggs, thimerosal, preservatives, gelatin, or latex.

Flublok, the world’s first recombinant protein-based vaccine for the prevention of seasonal influenza disease, was initially approved by the FDA in January 2013. The agency expanded its approval in October 2014 to include everyone over 18 years of age, and approved a nine-month shelf life in June 2016. 

Flublok is highly purified. In addition, it contains three times more antigen than traditional flu vaccines (3 × 45 mcg hemagglutinin protein versus 3 ×15 mcg hemagglutinin protein) and was shown to have better efficacy in a 2014–2015 postmarketing study. Flublok is an accurate copy of the virus coat and is not subject to the egg-adapted mutations that can be associated with low vaccine effectiveness.

Source: Protein Sciences Corporation; October 11, 2016.