400 volunteers are needed for the second round of testing of a bird flu vaccine, after the first phase of clinical trials showed that it is safe for human use.
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The second phase of clinical trials, being considered by the State Food and Drug Administration (SFDA), would test how long the vaccine would protect the human body against the deadly H5N1 virus, said Lin Jiangtao, one of the doctors leading the program at the Sino-Japanese Friendship Hospital where the first round of testing took place.
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"The second phase will need 300 to 400 volunteers," said Lin, adding that the exact number would be decided by the SFDA.
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Results from the first round, which ended in June, showed that the 120 people who were vaccinated had no serious adverse reactions.
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Lin said that mild fever after inoculation was a normal reaction.
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The trials indicated that a 10-microgram dosage of the vaccine gave the best results, stimulating 78.3 percent of protective antibodies, exceeding the European Union standard of 70 percent for a flu vaccine.
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The second phase would test similar dosages on volunteers to find out how best to stimulate the most antibodies, which requires a larger pool of volunteers, Lin said.
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Prospective volunteers should be aged 18 to 65, but children and pregnant women will not be allowed to participate.
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The vaccine must undergo three rounds of testing before it is allowed on the market, researchers said.
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Sinovac Biotech Limited, which jointly developed the vaccine with the Ministry of Science and Technology and the Center for Disease Control and Prevention, announced earlier this week that it would expand production facilities to produce massive quantities of human bird flu vaccine once testing is complete.

Bird flu remains essentially an animal disease, but experts fear that the H5N1 virus could mutate into a form that could spread easily among humans.
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The virus has killed 14 people in China since 2003.

(Xinhua News Agency September 1, 2006)