Biopharmaceutical company Vical Inc. (VICL) Tuesday said that its vaccine against A/H1N1 pandemic influenza, or swine flu, produced robust immune responses in preclinical studies with 100% response. The company also said that it is ready to advance directly to large-scale cGMP manufacturing of the vaccine for human clinical trials, subject to securing external funding for the program. In pre-market trading, Vical's shares climbed more than 26% to $2.79.
In the preclinical study, the vaccine's immune responses were well above the accepted protection threshold in 100% of vaccinated mice and rabbits after a standard two-dose vaccine regimen. In addition, at least 75% of vaccinated animals achieved or exceeded the protection threshold after a single dose of vaccine.
Vical said that its plasmid DNA vaccine contained the H1 hemagglutinin gene sequence provided by the U.S. Centers for Disease Control and Prevention or CDC for the A/H1N1 influenza strain selected on April 30. The preclinical vaccine was produced by May 11 and animal testing began on May 15.
In two parallel animal studies, one in mice and one in rabbits, the vaccine was administered on Day 0 and Day 21, a standard regimen for pandemic influenza vaccines. Sera collected on Day 21, after a single dose of vaccine, showed clear increases over baseline hemagglutination inhibition, or HI, titers in 100% of the animals, and HI titers above the protection threshold in 88% of the mice and 75% of the rabbits. Sera collected on Day 35, two weeks after the second dose, showed HI titers well above the protection threshold in 100% of the animals.
As per the company, the HI assay measures a vaccine's ability to prevent viruses from binding to cells, and HI titers of 40 or more are accepted as the threshold for potential protection against influenza viruses.
Commenting on the pre-clinical results, Vijay Samant, president and chief executive officer of Vical, said, "We are encouraged by these compelling data with our Vaxfectin-formulated DNA vaccine and we look forward to advancing to human clinical trials as soon as possible."
VICL closed Monday's trading at $2.20, down $0.20, on a volume of 1.43 million shares.
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June 05, 2026 16:18 ET A busy week for economic news flow saw a slew of reports being released that reflected the trends in the U.S. labor market. In Europe, economic growth and inflation data gained attention as the European Central Bank and Bank of England head for policy session later in the month. In Asia, the monetary policy session of the Indian central bank was in focus as the country, a major oil importer, reels under the pressures of a weaker rupee and rising inflation.