At least 800 volunteers will be needed for China's second and third phases of AIDS vaccine trials, health officials said Friday.

The second phase of clinical trials of China's AIDS vaccine would need at least 300 volunteers and the third phase at least 500, said Sao Guowei, director of the National Institute for the Control of Pharmaceutical and Biological Products.

Sang revealed the plan at a press conference held jointly by the State Food and Drug Administration (SFDA) and the Ministry of Science and Technology.

The later trials would involve participation of high-risk groups, said Chen Jie, deputy director of the Guangxi Regional Center for Disease Control and Prevention (CDC).

The first phase of clinical trials indicate China's first AIDS vaccine is safe and possibly effective, government officials announced at the press conference after a two-month-odd assessment.

"Forty-nine healthy people who received the injection showed no severe adverse reactions after 180 days, proving the vaccine was safe," said Zhang Wei, head of the pharmaceutical registration department of the SFDA.

"The recipients appeared immune to the HIV-1 virus 15 days after the injection, indicating the vaccine worked well in stimulating the body's immunity," he told the press conference.

The results mark the end of the first phase of the clinical trials of the AIDS vaccine, which focused on the vaccine's safety.

The first phase was launched in Nanning, capital of Guangxi Zhuang Autonomous Region, on March 12 last year. The volunteers, 33 men and 16 women aged between 18 and 50, had received the vaccine by October 20.

They were divided into eight groups. Six groups received a single AIDS vaccine and two other groups were injected with a combined AIDS vaccine, according to the Guangxi CDC.

Some recipients' cells and body fluids in the combined group appeared immune to the HIV-1 virus, said Sang Guowei.

"The HIV-1 specific cells injected into the recipients were the DNA fragments of the virus which don't cause infection," he told Xinhua.

A total of 344 blood samples were taken from the volunteers with each one donating five to ten samples, said Kong Wei, leader of the research team and a professor at Jilin University.

By June, all the volunteers had completed 180 days of observation and showed no serious ill effect, the Guangxi CDC announced on June 11.

The scientists were analyzing the results of the first phase and the SFDA would approve the second phase after a stringent assessment, SFDA officials said.

"It is a breakthrough in China's AIDS vaccine development, which was achieved by joint support from the central and local governments, scientific researchers, the public and international partners," said Liu Yanhua, Vice Minister of the Ministry of Science and Technology.

The State Food and Drug Administration approved the first phase of clinical trials of the new AIDS vaccine in November 2004.

Before that, China had had participated in several human trials of AIDS vaccine, but they were all carried out in other countries.

The new vaccine must undergo three phases of clinical trials before going into production. The second phase will assess both safety and immunity nature of the vaccine while the third will target the protection it offers for high-risk groups.

Estimates say China has approximately 650,000 people living with HIV, including approximately 75,000 AIDS patients.

A group of scientists and experts have advised the State Council, the Chinese cabinet, to raise funding for and encourage innovation and cooperation in research, warning the disease is spreading quickly to ordinary people.

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