May 23, 2004 15:52:00 (ET)

BEIJING, May 23, 2004 (BUSINESS WIRE) -- Sinovac Biotech Ltd. ("Sinovac") (NASD OTC-BB: SNVBF, Frankfurt: SVQ) is pleased to announce that it has commenced Phase I human clinical trials of its SARS vaccine. The first subjects were injected with the vaccine on the 22nd of May 2004 at the Sino-Japan Friendship Hospital in Beijing, China. More details will follow in a follow-up Sinovac news release on the 24th May 2004.

About SARS

The first subjects were injected with the vaccine on Saturday the 22nd of May 2004, at the China-Japan Friendship Hospital in Beijing, China. The four volunteers, three healthy male students and a female student, were injected with either the SARS vaccine or a placebo.

No abnormal reaction was observed during the two-hour observation period after inoculation, and the volunteers left the hospital. Dr. Wei Dong Yin, president of Sinovac, updated on Sunday that the four volunteers are in excellent health after the first day of the SARS vaccine clinical testing.

The clinical trial commencement was attended by several high-ranking representatives of the Chinese government, including: Mr. Guanhua XU, the Minister of Science and Technology of China and Mr. Xiaoyu ZHENG, the Director General of the Chinese FDA (SFDA).

Sinovac is the only company in China, and indeed the world, to have been approved to conduct human clinical trials of a SARS vaccine.

Clinical Trial Design

There are 36 healthy volunteers aged from 21 to 40 that were selected for clinical testing, who are divided into four groups. Twenty-four subjects (two groups of 12) will get the vaccine, and the twelve others (two groups of 6) will get the placebo. Each subject will get two shots. The first shot is on day 0 followed by 28-day observation of the subject. The second shot will be given after the initial 28 day period and the subject will be observed until day 210, the phase I trial end-date.

The volunteers will be observed for reaction every day for the first three days, and then less frequently throughout the whole 210-day observation process. Neither the volunteers nor the administering doctors were informed of whether the injection was a vaccine or a placebo. The 4 above-mentioned volunteers are the first to have been inoculated out of the group of 36 subjects.

Regulatory Approval Process

The drug approval process regulated by the State Drug Administration (SFDA) in China is similar to the one regulated by the FDA in the United States. The process involves pre-clinical in vitro laboratory and in vivo animal testing; IND study (Investigational New Drug); human clinical Phases I, II and III; New Drug Application; and finally Marketing Approval for sale.

The SFDA has stated that it is fast-tracking the drug approval process for Sinovac's potential SARS vaccine.

As previously announced, pre-clinical trials on Rhesus monkeys showed Sinovac's vaccine was effective in preventing infection. The monkeys that were inoculated with the vaccine experienced no serious side effects after they were exposed to the potentially deadly virus.

Immune response was invoked by the vaccine in all animal models. No immune enhancement was observed in any of the pre-clinical testing.

Sinovac was approved to commence Phase I clinical trials on the 19th January 2004. Since that time, Sinovac has been fulfilling the requirements for the actual commencement of the clinical trial. First of all, the specific vaccine to be used in the trial was manufactured. Then, this vaccine and the placebo were submitted to the National Institute for the Control of Pharmaceutical and Biological Products (NICPBP) for testing. The testing reports were received on April 21st and 23rd of 2004 and the vaccine was proven to be eligible for use in the trial by the NICPBP. Sinovac then coordinated its clinical efforts by setting up an Ethics Committee for the trial. Finally, the screening of the clinical subjects selected for the trial was carried out. The SFDA approved the commencement of the Phase I clinical trial and will be monitoring the trial for its duration.

Clinical protocols for the testing of Sinovac's potential SARS vaccine have been developed in accordance with stringent newly established worldwide protocols for the conduct of SARS vaccine clinical trials. The protocols were also developed with the cooperation of the Chinese FDA (SFDA), China CDC, and the China Medical Academic College.

The ultimate aim of the vaccine will be to provoke the body's immune system into action, so that it can destroy the SARS virus if infected.

The first phase of human testing will determine if the vaccine is safe for the human body. Risks do exist but, if any, they are anticipated to be only minor, such as low fever and pain. During and after the Phase I trial, analysis will be conducted. The summary report will be sent to the SFDA for its review and if the vaccine receives SFDA approval, then it will proceed into Phase II clinical trials. A second phase of clinical testing would have more participants from a wider demographic range.

During the Phase I clinical trial, Sinovac will provide continuous updates on the status of the trial and the health condition of the volunteers.

ABOUT SARS

SARS, a viral respiratory illness caused by a coronavirus, was first reported in Asia in February 2003, and over the following few months, the illness spread to more than two dozen countries in North America, South America, Europe, and Asia. According to the World Health Organization, during the SARS outbreak of 2003, a total of 8,098 people worldwide became sick with SARS; of these, 774 died. The SARS global outbreak of 2003 was contained; however, it is expected that the disease could re-emerge in an annual cycle similar to the common flu.

ABOUT SINOVAC BIOTECH LTD.

Sinovac Biotech Ltd. specializes in the research, development, commercialization, and sales of human vaccines for infectious illnesses such as Hepatitis A and Hepatitis B, influenza and "SARS". Sinovac is one of the leading emerging biotechnology companies in China. Working closely with Chinese public health officials, Sinovac focuses on manufacturing and marketing human-use vaccines and related products, and currently markets its vaccine for Hepatitis A. Sinovac is the first and currently the only company in the world to have commenced human clinical trials for a vaccine to prevent SARS.

For further information please refer to the Company's filings with the SEC at www.sec.gov or refer to Sinovac's website at www.sinovac.com.

THIS NEWS RELEASE MAY INCLUDE FORWARD-LOOKING STATEMENTS WITHIN THE MEANING OF SECTION 27A OF THE UNITED STATES SECURITIES ACT OF 1933, AS AMENDED, AND SECTION 21E OF THE UNITED STATES SECURITIES AND EXCHANGE ACT OF 1934, AS AMENDED, WITH RESPECT TO ACHIEVING CORPORATE OBJECTIVES, DEVELOPING ADDITIONAL PROJECT INTERESTS, SINOVAC'S ANALYSIS OF OPPORTUNITIES IN THE ACQUISITION AND DEVELOPMENT OF VARIOUS PROJECT INTERESTS AND CERTAIN OTHER MATTERS. THESE STATEMENTS ARE MADE UNDER THE "SAFE HARBOR" PROVISIONS OF THE UNITED STATES PRIVATE SECURITIES LITIGATION REFORM ACT OF 1995 AND INVOLVE RISKS AND UNCERTAINTIES WHICH COULD CAUSE ACTUAL RESULTS TO DIFFER MATERIALLY FROM THOSE IN THE FORWARD-LOOKING STATEMENTS CONTAINED HEREIN.

SOURCE: Sinovac Biotech Ltd.

Sinovac Biotech Ltd.
Investor Relations, 888-888 8312 or 604-684-5990
info@sinovac.com

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