Following a six-month trial expansion, seen as crunch-time for the vaccine, the company will increase its annual output from 8 million doses to 20 million.

If two further rounds of clinical trials prove successful, production of a human bird flu vaccine will be greatly accelerated, Beijing Sinovac Biotech Co announced on Tuesday

Following a six-month trial expansion, seen as crunch-time for the vaccine, the company will increase its annual output from 8 million doses to 20 million. The human bird flu vaccine was developed jointly with China's Ministry of Science and Technology, and China Disease Control and Prevention Center.

Preliminary clinical tests have shown that the vaccine is safe and effective for human use, researchers said.

"These results indicate that we should expand our production capabilities to prepare for mass vaccine production against a possible bird flu pandemic," the company's spokesman said.

Results from the first round of trials, which ended in June, showed no adverse effects in the 120 test subjects.

In China, a vaccine is allowed to enter the market after completing three phases of clinical trials.

Bird flu remains essentially an animal disease, but experts fear the H5N1 virus could mutate into a form that could be contracted from person to person.

Worldwide, about a dozen companies are conducting clinical trials on bird flu vaccines.

According to the World Health Organization, the H5N1 virus has proven difficult to predict, and as drug companies move forward with their pandemic vaccine development, they may be gambling on which strain is most likely to mutate into the virus' dreaded form.

The virus has killed 14 people in China since 2003 among 21 sufferers. The latest case involved a 62-year-old man in Xinjiang Uygur Autonomous Region, who died on July 12.

(Xinhua News Agency August 30, 2006)