Vaccine Shows Efficacy Against H7N9 Bird Flu
Seroprotection induced in 81% of recipients (November 13)
Positive clinical data for a virus-like particle (VLP) vaccine candidate against A(H7N9) influenza (Novavax, Inc.) have been published online in the Correspondence section of the New England Journal of Medicine.
The study, conducted in 284 men and women, examined the safety and immunogenicity of two administrations of the A(H7N9) VLP vaccine candidate on day 0 and day 21. The subjects were given placebo; 15 mcg or 45 mcg of vaccine alone; or 5 mcg or 15 mcg of vaccine with either 30 or 60 ISCO units of the saponin-based Iscomatrix adjuvant. Serology was assessed on days 0, 21, and 35 after first immunization.
The A(H7N9) VLP vaccine candidate induced hemagglutination-inhibition (HAI) antibody titers of ≥ 1:40 (seroprotection) and a four-fold HAI antibody increase (seroconversion) against H7N9 in 81% of subjects at the 5-mcg dose of A(H7N9) antigen with 60 ISCO units of adjuvant, and in 73% of subjects receiving the 5-mcg dose of A(H7N9) antigen with either adjuvant dose level. The vaccine also elicited anti-neuraminidase antibodies against N9 in 92% to 97% of subjects receiving the 5-mcg dose with either adjuvant dose level.
The A(H7N9) VLP vaccine candidate was generally well tolerated. Overall, as with other adjuvanted influenza vaccines, there was an increase in transient local and systemic reactions with the adjuvanted formulations in contrast to the non-adjuvanted formulations, but no treatment-related serious adverse events were observed in any of the active treatment groups.
Iscomatrix adjuvant is made from saponin, cholesterol, and phospholipid which, under defined conditions, form cage-like structures typically 40 to 50 nm in diameter.
Source: Novavax, Inc.; November 13, 2013.