GlaxoSmithKline scientists Monday in Hong Kong said an experimental flu vaccine appears to protect against infection with the H5N1 bird flu at very low doses and also protects against a varient of the virus that doesn't match the one in the vaccine.
Researchers said their vaccine causes a significant immune response at a lower dose than usually required when it's mixed with an immune booster called an adjuvant. It also protects against mutated bird flu strains, tests in animals indicate.
More studies will be needed before the vaccine can be evaluated for approval by the Food and Drug Administration, company officials said, and those tests will begin this year.
"Those are potentially major breakthroughs," said infectious-disease specialist Andrew Pavia of the University of Utah Medical Center, chair of the Infectious Diseases Society of America's pandemic flu committee, who is not involved with GSK or its research.
And being able to make it using such low doses could have a "huge public health impact" by increasing the vaccine supply, Pavia said.
In reports presented at the International Symposium on Respiratory Viral Infections, scientists said an experimental vaccine containing 3.8 micrograms along with the adjuvant was 25 times more powerful than the same dose without the adjuvant. A second study in ferrets found the vaccine not only protected against the Vietnam H5N1 flu strain in the vaccine, but also against a newer version that emerged in Indonesia.
Last week, an FDA advisory committee recommended approval of an H5N1 vaccine made by Sanofi Pasteur. That vaccine requires two 90-microgram shots given four weeks apart to prompt an immune reaction strong enough to prevent illness.
But Pavia said the GSK vaccine still needs to go through FDA review, and because the adjuvant that is crucial to the vaccine's strength is new, "it means there's a lot to learn about safety.
GSK's Bruce Ennis, vice president of Research and Development for Vaccines, said the license application for the company's vaccine has been accepted for review by European regulators, and "we are in discussion with the FDA" about studies needed for license applications to be made in the USA. He said clinical trials in the U.S. will begin this year.
