The study enrolled healthy volunteers 18 to 49 years in age who were immunized with a single injection of Novavax’s trivalent seasonal influenza VLP vaccine matched to the influenza strains recommended for the 2008-2009 influenza vaccine.
The complete analysis included 232 volunteers in total; with 49 receiving placebo, 83 given Novavax’s trivalent seasonal influenza VLP vaccine at 15 mcg/dose, 81 injected with Novavax’s trivalent seasonal influenza VLP vaccine at 60 mcg/dose and 19 volunteers receiving an inactivated trivalent influenza vaccine Fluzone (TIV) at 15 mcg/dose.
The three strains were H1N1 A/Brisbane/59/2007, H3N2 A/Brisbane/10/2007, and B/Florida/04/2006. The data show that Novavax’s trivalent seasonal influenza VLP vaccine induced a robust hemagglutination inhibition (HAI) antibody response against all three strains in the vaccine.
Preliminary HAI results from this study were presented at the 47th Annual Meeting of the Infectious Diseases Society of America (IDSA). The interim results were based on evaluation of a total of 190 volunteers, of which 37 received placebo, 69 received trivalent seasonal influenza VLP vaccine at 15 mcg/dose, 67 received trivalent seasonal influenza VLP vaccine at 60 mcg/dose and 17 received TIV.
In the final results reported, the H3N2 and B strain data in the 15 mcg VLP dose met the FDA seroconversion guidelines of 40 (lower 95% CI) while the H1N1 data fell just short (39.4 versus 40.0). However, the mean seroprotection rate against the H1N1 strain rose slightly from an original 67% to a final 70%.
In addition to the HAI titers, functional antibody against the Neuraminidase enzyme was measured in the sera of immunized subjects using a neuraminidase inhibition assay (NAI). Inhibition of neuraminidase activity may be important in reducing the spread and severity of influenza infection.
Rahul Singhvi, president and chief executive officer of Novavax, said: “The data released today show that our VLP influenza vaccine not only induces a robust HAI response but also enhances the NAI response far above that induced by TIV. We will continue measurement of NAI activity in other clinical trials since we believe that the ability of the VLP vaccine to elicit an NAI response may differentiate our vaccine from others.
“These NAI results support our position that VLP influenza vaccines have the potential to induce a broad-based immune response that could lead to improved clinical outcomes. We now await comparative immunological and safety data from a larger head to head clinical trial in older adults (>60 years of age) between TIV and our VLP vaccine.”