Beginning from late Wednesday, China's 13,300 volunteers who took part in clinical trials of domestically-developed vaccines against the H1N1 flu began to receive the final second shot, according to a notice issued by the Ministry of Health.

No case of severe adverse drug reaction has been reported so far, ministry officials said.

The volunteers will be studied by an expert team from the health ministry and further results will be compiled in mid August, said Wang Yu, director of the Chinese Center for Disease Control and Prevention (CDC).

All clinical trials of China's vaccines were supervised by the CDC, he said, adding that safety was the top priority in the vaccine's research and development.

Health Minister Chen Zhu took the lead on Tuesday by receiving his second inoculation of the vaccine. Chen received the first shot in China on July 22.

"He might also be the first in the world to receive the first one," said Liu Peicheng, spokesman of the Beijing-based Sinovac Biotech Company, which made the vaccine Chen received.

Experts will probably make the final assessment of the vaccine in terms of safety and effectiveness in mid September, he told China Daily yesterday.

On July 22, volunteers for human trial began to get the first shot of the vaccine developed by 10 designated vaccine producers in the country.

Most of them are also making seasonal flu vaccines.

Health scientists with the CDC called on the public to get vaccinated against seasonal flu by the end of September to avert potential cross infections.

Each year, an average of only 26 million people in China voluntarily receive the shot, official statistics show.

Similarly, not everyone in China needs to be vaccinated against H1N1, said Liang Wannian, deputy director of the emergency response office under the Ministry of Health.

"The coming vaccine would be mainly targeted at high-risk groups - people with prevalent illnesses and pregnant women," he said.

The inoculation plan will be released by the ministry early next month, Xinhua News Agency reported.

The amount of vaccine needed for 130 million people, one tenth of China's population, will be ready by the end of October, said Liang. All of the vaccine produced will enter the State strategic stockpile instead of the market, he added.

World Health Organization officials stressed that safety should not be compromised despite the urgency to approve the vaccines for use.

As of August 12, the Chinese mainland had confirmed 2,425 cases of H1N1 influenza, with no fatal cases.

(China Daily August 14, 2009)