Flublok [Influenza Vaccine] is a sterile, clear, colorless solution of recombinant hemagglutinin (HA) proteins from three influenza viruses for intramuscular injection. It contains purified HA proteins produced in a continuous insect cell line that is derived from cells of the fall army worm, Spodoptera frugiperda, and grown in serum-free medium composed of chemically-defined lipids,
