China is stepping up efforts to make and distribute a new vaccine to stop the spread of the bird flu virus known as H5N1, and says it plans to produce one billion doses by the end of the week.
State media quoted China's Agriculture Ministry as saying the one billion doses are to be administered to birds early next year, part of a larger effort to immunize more than 14 billion poultry.
Not all experts agree that vaccination is the best way to go. The World Health Organization's top official in China, Dr. Henk Bekedam, said recently that longer-term solutions, such as keeping farm animals separate from humans, are necessary, since the virus could mutate and render vaccines useless.
"We don't know if the H5N1 is a precursor [to another virus]. Perhaps, it will be overtaken by something completely different. In the poorer rural areas, it's an enormous challenge," said Dr. Bekedam.
Bird flu is known to have killed 73 people in Asia, two of them in China. While most infections have been from bird to human, researchers fear the strain may mutate, so it could be passed easily from person-to-person.
Chinese officials say their new vaccine, which can be given orally, will be effective not only against H5N1, but also against Newcastle's disease, an illness that officials said killed 57,000 chickens in China earlier this year.
China has embarked on a massive effort to stop the spread of bird flu by culling or vaccinating millions of chickens and domesticated ducks. Vietnam and Indonesia have launched similar campaigns.
China's program came under criticism last month, when foreign media reported that vaccines were in short supply and were sometimes being administered by poorly trained staff, raising further questions about the effectiveness of such a massive vaccination program.