Bird Flu Vaccine: Will It Work?

July 26, 2006 — -- GlaxoSmithKline's announcement that it has a promising bird flu vaccine in development may help to ease the public's fears. However, it's still not clear whether this new vaccine will help prevent a bird flu pandemic, said many scientists.

The pharmaceutical company's president said today that Glaxo has successfully developed a vaccine that created an effective immune response against bird flu in 80 percent of the 400 people tested.

This isn't the only potentially effective bird flu vaccine on the market. What makes this vaccine different from others is that it contains a much lower dose of the inactivated virus than other formulations. While the Glaxo vaccine uses 3.8 micrograms of vaccine, other versions contain about twice as much flu virus, said Dr. Donald J. Kennedy, a professor of infectious diseases at St. Louis University.

Glaxo's president, David Stout, touted the new vaccine as a breakthough: Because Glaxo's vaccine uses a much lower dose of the virus, it can be mass produced in a shorter amount of time.

But for now, scientists urged caution.

"Even if approved, it still takes four to six months to produce, and if a strain mutates, either some or a lot it can lose its effectiveness," Kennedy said. "The public should be cautioned on this."

Also, it contains a new type of adjuvant, or compound that boosts the body's immune response.

The U.S. Food and Drug Administration has hesitated to approve adjuvants, said David Topham, a microbiology professor at the University of Rochester, as they can cause side effects such as swelling and tenderness.

"You don't want to put anything [in] a healthy person that can cause a problem," Topham said.

So far, this vaccine has only been tested in 400 healthy adults, said Dr. William Schaffner, chairman of the department of preventive medicine at Vanderbilt University. It still needs to be tested in older adults and children.

"They're ahead of the parade a bit, obviously blowing their own horn," Shaffner said.

There also is the question of whether a vaccine developed today will protect against a virus of tomorrow. All flu viruses, including H5N1, mutate quickly.