FDA Approves First Trivalent Influenza Vaccine Made Using Recombinant Technology

The FDA's recent approval of a trivalent seasonal influenza vaccine made using novel manufacturing technology marks a significant milestone in the ongoing battle against this life-threatening illness. According to a Jan. 16 FDA release, Flublok, which is approved for use in adults ages 18-49, does not rely on the traditional method of growing the targeted influenza virus strains in chicken eggs and, thus, can be produced more rapidly than current vaccines.

Protein Sciences Corp. of Meriden, Conn., which manufactures Flublok, said the vaccine is the first such antitoxin that does not require the use of chicken eggs or live viruses during the production process. Instead, the company uses an insect virus (baculovirus) expression system and recombinant DNA technology to generate purified hemagglutinin antigens specific to each flu virus strain included in the annual vaccine.

"This approval represents a technological advance in the manufacturing of an influenza vaccine," Karen Midthun, M.D., director of the FDA's Center for Biologics Evaluation and Research, said in the agency's release. "The new technology offers the potential for faster start-up of the vaccine manufacturing process in the event of a pandemic because it is not dependent on an egg supply or on availability of the influenza virus."

In addition, according to Protein Sciences Corp. (6-page PDF; About PDFs), the new vaccine does not use the whole influenza virus or eggs in its production, so it is safe for people with egg-related allergies. Moreover, the preservative-free vaccine is formulated to contain three times the active ingredients found in other available flu vaccines and may confer greater immunogenicity in elderly and immunocompromised patients.

In its release, the FDA noted that the vaccine's effectiveness was evaluated in a study comparing about 2,300 people vaccinated with Flublok to a control group of similar size that was given a placebo.

"Flublok was about 44.6 percent effective against all circulating influenza strains, not just the strains that matched the strains included in the vaccine," the release said. "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."

Lisa Dunkle, M.D., chief medical officer for Protein Sciences Corp., told AAFP News Now that the company will distribute approximately 100,000 doses in 2013, primarily to pre-identified customers and practices that have special needs. At the same time, Dunkle said, the company is expanding to a new manufacturing facility, which it expects will allow it to offer 3-5 million doses during the 2013-14 season.

"We are also currently conducting a safety study to support FDA approval for all adult ages and anticipate approval by the end of November 2014," said Dunkle. "And we plan to initiate studies in the pediatric population in the near future."