By Xinhua writers Li Xing, Cui Qingxin

    BEIJING, Aug. 18 (Xinhua) -- 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 Sang 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 Ministry of Science and Technology.

    The later trials would involve the 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 indicates 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 Oct. 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 volunteers were paid 2,000 yuan (250 U.S. dollars) for their participation, which was set by the Chinese Medicine and Ethnics Society.

    They signed an agreement with the Guangxi CDC for getting the injection, which is responsible for future possible adverse reactions from the vaccine, said one of the volunteers Peng Zhi.

    "We were told the vaccine contains no live HIV virus and we wouldn't be infected by getting the injection, and only partial inflammation or pain might occur due to individual differences," said Peng, a student from the Guangxi Medical University.

    Half of the volunteers are from the university. Others include government employees.

    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 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 participated in several human trials of AIDS vaccines, 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.

    By the end of 2005, China had recorded more than 140,000 people infected with HIV. Officials estimate that China has approximately650,000 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.

    According to the report disclosed at Friday's press conference, there have been 120 AIDS vaccine tests on humans throughout the world. The ongoing tests in China include 29 in phase I, four in phase I and II, three in phase II and one in phase III.

    The phase-III tests on the first-generation vaccine failed, the report said.

    China's research into AIDS vaccines has been going on for 15 years but the country does not have the intellectual property rights over its AIDS vaccines in trial and the research has limited global influence, the report said.

    The total infections of HIV in the world had exceeded 40 million and more than 30 million AIDS patients had died by the end of 2005, according to figures released by the World Health Organization (WHO) and the Joint United Nations Programme on HIV/AIDS (UNAIDS). Enditem