FDA approves new seasonal flu vaccine made using novel technology

FDA approved the first trivalent influenza vaccine (Flublok, Protein Sciences) made using an insect virus (baculovirus) expression system and recombinant DNA technology for the prevention of seasonal influenza disease in people aged 18 to 49 years. 

It is the first vaccine to be made in a 100% egg-free system without growing influenza viruses, so the vaccine can be made quickly and without any of the infectious risk traditionally associated with vaccine manufacture.  Flublok is highly purified, has 3 times the amount of active ingredient in traditional influenza vaccines, and contains no preservatives (thimerosal), antibiotics or adjuvants, according to a company press release.

“Flublok is truly a modern vaccine,” Manon Cox, CEO of Protein Sciences said in a company press release. “We use advanced scientific technology to make just the active ingredient of the vaccine without any other viral components.  This is the first influenza vaccine on the market to do so.” 

As it does with all influenza vaccines, FDA will evaluate Flublok annually prior to use by the public each flu season. The recombinant HA proteins produced in the baculovirus expression system and included in Flublok will be assessed by FDA.


The effectiveness of Flublok was evaluated in a study conducted at various sites in the United States that compared the use of Flublok in about 2,300 people to a placebo that was given to a control group of similar size. Flublok was about 44.6% effective against all circulating influenza strains, not just the strains that matched the strains included in the vaccine. Flublok’s safety evaluation was conducted in a study of about 2,500 people who were vaccinated with Flublok. The most commonly reported adverse events included pain at the site of injection, headache, fatigue, and muscle aches, events also typical for conventional egg-based, inactivated influenza vaccines.

Flublok has a shelf life of 16 weeks from the date of manufacture. Healthcare providers should check the expiration date before administering Flublok.