Even though officials in the United States say more testing needs to be done, the U.S. could begin mass production of an experimental avian flu vaccine by September.
In successful tests carried out on 450 healthy adults, results from 115 of those people have shown a high enough immune response to protect against the avian flu presently rife amongst birds in Asia and also now in Russia.
The head of the U.S. National Institute of Allergy and Infectious Diseases, Dr. Anthony S. Fauci, says he expects the other 335 patients to show a good response too.
Fauci says if the vaccine is effective, it will be a major step forward in preventing what many think will be the next pandemic flu.
However many experts feel that while the development is important, there is still a long way to go in deciding how much is put in each dose, how many doses are given, and how long it lasts for.
Researchers have already found that the current avian flu vaccine formulation requires a higher dose than seasonal flu vaccines, in order to trigger an immune response, and the elderly are likely to require even higher doses.
The government have apparently already ordered two million doses from a French manufacturer, but if testing indicates the formula should be changed that will not be possible.
According to Mike Leavitt, the U.S. Health and Human Services Secretary, the federal government wants to stockpile 20 million doses of the vaccine.
However pharmaceutical companies usually only make enough flu vaccine to cover the most vulnerable members of society, the elderly, children and the sick.
But it is thought that it might be possible for companies to make the seasonal flu vaccine and the bird flu vaccine at the same time.
The last pandemic, the Spanish Flu of 1918, killed 50 million people worldwide, and was in an era before air travel.
Many health experts have warned for months that if a pandemic evolves in Asia, it is only a matter of time before it ends up all over the world.
That the avian flu is already appearing in a number of countries, raises the level of concern.