Sinovac Biotech Ltd, a leading provider of vaccines in China, released positive top-line results of completed phase II clinical trial of its pandemic influenza (H5N1) whole viron inactivated vaccine. The stratified, randomised, double-blind trial of the vaccine was designed to assess the safety and immunogenicity of the vaccine.

Sinovac received approval from the China State Food and Drug Administration (SFDA) in April 2007 to conduct phase Ib and II trials of the H5N1 whole viron vaccine and phase I and phase II trials of the H5N1 split vaccine.

The phase II trial of the H5N1 whole viron inactivated vaccine was conducted by Beijing Centres for Disease Control and Prevention. It included 402 volunteers, between the ages of 18 and 60, who were each vaccinated with two doses of 5 ug, 10 ug or 15 ug. The preliminary results of the trials suggested that each of the three dosages can induce varying degrees of immune response. In particular, the anti-HI seroconversion rate, the increasing GMT and protection rate of the H5N1 whole viron inactivated vaccines for the 10ug and 15ug dosages reached the EMEA evaluation standards of seasonal flu vaccines, which is an indication of good immunogenicity of the vaccine. The trial result did not show any serious adverse reaction among volunteers, suggesting the vaccine's good safety profile.

In addition, Sinovac recently completed the phase I clinical trial of the split H5N1 vaccine. The result of vaccinations on children, adults and elderly with candidate vaccines of different dosage indicated that the split H5N1 vaccine is safe for human use.

Weidong Yin, chairman, president and CEO, stated, "We are very pleased with the achievements of our team that led to the development of a pandemic influenza vaccine. After Phase II clinical trials of the whole viron H5N1 vaccine, the vaccine dosages and schedule can now be determined. This accomplishment is a further step towards providing an effective prevention option for the government in the event of a future influenza pandemic. In addition to announcing the positive results of the Phase II clinical trial for the H5N1 whole viron vaccine, we are making progress on the clinical trials for the H5N1 split vaccine, which should provide additional prevention options in the face of a future influenza pandemic."

Sinovac commenced the development of a pandemic influenza vaccine in February 2004. In June 2006, the phase I clinical trial results indicated good immunogenicity and safety, which results were published in "The Lancet" in September 2006.

Sinovac Biotech Ltd. is a China-based biopharmaceutical company that focuses on the research, development, manufacture and commercialisation of vaccines that protect against human infectious diseases. Sinovac is currently developing human vaccines against the H5N1 strain of pandemic influenza, and Japanese encephalitis.