Novavax (NVAX) Announces Poster Presentation of Seasonal Flu VLP Vaccine, Including H1N1

November 2, 2009 9:12 AM EST

Novavax, Inc. (NASDAQ: NVAX) announced today that the Company made a poster presentation on the "Safety and Immunogenicity of a Recombinant Trivalent Seasonal Influenza Virus-like Particle (VLP) Vaccine in Healthy Adults" on Saturday, October 31, 2009 at the 47th Annual Meeting of the Infectious Diseases Society of America (IDSA).

This presentation included data from a study of Novavax's trivalent seasonal influenza VLP vaccine that began in May of this year among healthy adults 18 to 49 years of age. The vaccine contained VLPs matched to the influenza strains recommended for the 2008-2009 influenza vaccine including H1N1 A/Brisbane/59/2007, H3N2 A/Brisbane/10/2007, and B/Florida/04/2006. The study enrolled 241 subjects in total, including 221 who were randomized to receive either VLP vaccine at 15 mcg or 60 mcg or a placebo and 20 subjects who received an inactivated influenza vaccine (TIV).

The trivalent seasonal influenza VLP vaccine was well tolerated and immunogenic. The incidence of adverse events was comparable in the VLP vaccine groups (10.6%) and the placebo group (11.8%). No serious vaccine-related adverse events have been reported to date. The VLP vaccine induced robust hemagglutination inhibition (HAI) antibody responses against all three strains in the vaccine and a drifted strain. Seroconversion (greater than or equal to 4-fold rise in titer from baseline) rates met the suggested FDA criteria for licensure of seasonal influenza vaccines for all three strains. For subjects in the 15 mcg group, seroconversion rates (95% CIs) were 57% (44, 68), 86% (75,93), and 62% (50,74) against the H1N1, H3N2, and B strains, respectively. Seroprotection (titer greater than or equal to 1:40) rates met the FDA criteria for licensure for all strains except the H1N1 strain. For subjects in the 15 mcg group, seroprotection rates (95% CIs) were 67% (54,78), 91% (82,97), and 84% (73,92) against the H1N1, H3N2, and B strains, respectively. Interestingly, the FDA seroconversion and seroprotection criteria were also met for a drifted H3N2 strain, A/Wisconsin/67/05, which was included in the 2006-2007 influenza vaccine. The seroconversion and seroprotection rates against this strain were 77% and 93%, respectively, among subjects in the 15 mcg group.

Antibody responses were observationally compared among VLP vaccine and TIV recipients although the sample size for the TIV group was too small to support definitive conclusions. In this small study, HAI responses against the H1N1 and B strains were statistically indistinguishable and HAI responses against the H3N2 A/Brisbane strain appeared higher in VLP as compared with TIV recipients. These results support moving forward with a larger head-to-head study of the VLP vaccine as compared with TIV.

In addition to the HAI responses, although not presented in the poster, functional antibody against the Neuraminidase enzyme was measured in the sera of immunized subjects using a neuraminidase inhibition assay (NAI) developed by Novavax scientists. Inhibition of neuraminidase activity may be important in reducing the spread of influenza virus down the respiratory tract and severe influenza disease. Preliminary data indicate that the trivalent seasonal influenza VLP vaccine induced functional antibody that inhibits neuraminidase activity of Types A and B influenza viruses.

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