Trials of the vaccine on 400 healthy Belgians, aged 18 to 60, demonstrated that at its lowest dosages the vaccine proved to give protection to 80 percent of subjects.
The British company's vaccine uses a proprietary adjuvant, an additive that boosts the immune system into responding to the vaccine's antigen more effectively. The vaccine uses an inactivated version of the H5N1 strain, which was isolated in Indonesia last year.
"With this adjuvant added to the vaccine, provided the rest of the tests are OK, you could make 10 times as much vaccine," said Dr. Albert Osterhaus, head of the virology department at Erasmus University in the Netherlands.
The surprisingly low amount of vaccine, two doses of 3.8 micrograms, overcomes an obstacle for vaccine companies to produce enough doses to protect millions of people around the world using the minimum amount antigen.
A previous study on a vaccine from French competitor Sanofi-Aventis SA protected only about 50 percent of its test subjects, who received two shots with much higher doses of 90 micrograms each.
"It changes the whole complexion of the issue that we have to face of getting enough vaccine for people who might need it in a pandemic," said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases.
Glaxo chief executive Jean-Pierre Garnier hopes to seek approval from the Food and Drug Administration and authorities in other countries within the year. "All being well, we expect to make regulatory filings for the vaccine in the coming months," he said. Providing the company exhibits solid data, the vaccine will be likely placed in an accelerated approval process, said FDA spokesman Paul Richards.
Following recent meetings between Garnier and President Bush to discuss the bird flu threat, GlaxoSmithKline received $272 million to investigate technologies to improve the mass production of flue vaccine. The company is capable of producing 60 million to 70 million doses of seasonal flu vaccine and up to 150 million doses by 2008.
Although the vaccine may work against the current form of the H5N1 strain of bird flu, scientists are wary about how effective it will be on any future form of the virus.
The H5N1 strain of the bird flu spreading around the world is not easily transmitted between humans, but a pandemic flu could develop if the virus mutated into a more contagious strain. The virus is found mostly in birds but can be lethal to humans, killing half of those infected.
"This is very promising technology, but what is still not known is how well this vaccine will work on whatever the actual strain is that produces a pandemic," said Dr. Irwin Redlener, head of the National Center for Disaster Preparedness at Columbia University.
The H5N1 strain was first discovered in Hong Kong in 1997 and has spread to the rest of Asia, Europe and Africa through birds. Of the 232 people in 10 countries who have contracted bird flu, 134 have died.