Baxter International Inc, Deerfield, Ill, has unveiled results from a preliminary evaluation of its Phase I/II clinical trial of whole-virus H5N1 influenza candidate vaccine. The results represent the first clinical evaluation of a vero cell-based candidate H5N1 pandemic vaccine.

The candidate H5N1 pandemic vaccine was produced using the company’s proprietary vero cell-based technology platform and inactivated wild-type H5N1 strain A/Vietnam/1203/2004.

“This is the first clinical demonstration that a candidate H5N1 vaccine can induce antibodies that neutralize widely divergent strains of H5N1,” said Hartmut Ehrlich, MD, vice president of global research and development for Baxter BioScience. “These preliminary data, which must be confirmed in a larger study, suggest that the vaccine may provide wider protection for a larger number of people before and during a pandemic.”

Preliminary results from this trial suggest that the vaccine is well tolerated in humans: the occurrence and severity of side effects at all dose levels are similar to what has been reported for licensed interpandemic (or seasonal) influenza vaccines. Most common side effects are injection site reactions, headaches, and fatigue. In addition, the preliminary results suggest that the vaccine is highly immunogenic and elicits functional antibodies to H5N1 even at the lowest dose level of 3.75mcg.

“These preliminary results are encouraging,” said Professor Frank von Sonnenburg, MD, who heads the Section of International Medicine and Public Health within the Department of Infectious Diseases and Tropical Medicine at the University of Munich, and chairs the Data Safety and Monitoring Board for the clinical study. “If confirmed in Phase III results, the suggested safety and immunogenicity of this cell-culture derived whole virus vaccine indicate its potential to make a major contribution to public health in preparing for and combating an influenza pandemic situation.”