THURSDAY, Jan. 17 (HealthDay News) -- Flublock, a new vaccine that uses recombinant DNA technology to prevent the flu, has been approved by the U.S. Food and Drug Administration for people aged 18 to 49.

Flublock doesn't use traditional flu vaccine components -- including the influenza virus or eggs -- in its production. Instead, it uses an insect virus (baculovirus) to produce large amounts of the influenza virus protein, hemagglutinin (HA). Most antibodies that prevent flu infection are directed against HA, the FDA explained in a news release.

"This approval represents a technological advance in the manufacturing of an influenza vaccine," Dr. Karen Midthun, director of the FDA's Center for Biologics Evaluation and Research, said in the news 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."

The vaccine can be modified before each flu season to include the most predominant flu strains, the agency said.

The product's effectiveness was evaluated in a study that compared use of Flublok in about 2,300 people to a control group of a similar size that was given a placebo. The vaccine was about 44.6 percent effective in preventing infection with all circulating strains of flu, not just those included in the vaccine, the FDA said.

The most common side effects noted were injection-site pain, headache, fatigue and muscle aches -- typical adverse reactions among conventional flu vaccines.

Flublok is produced by Protein Sciences Corp., based in Meridan, Conn.

More information

The FDA has more about this approval.