Study Overview

This clinical trial is a Phase 2a, randomized, double-blind, controlled study in 138 adult subjects to compare the immunogenicity and the safety of the OVX836 influenza vaccine at two dose levels (300μg and 480μg) to lower dose level (180µg) and to placebo. One dose of OVX836 influenza vaccine (180µg or 300µg or 480µg) or placebo will be administered intramuscularly in healthy subjects aged 18-55 years and in healthy subjects aged 65 years and older.

Study Results

Participants were recruited between Nov 15, 2021, and Feb 1, 2022. OVX836 had a favorable safety profile up to 480 μg without reaching the maximum tolerated dose and showed a good safety profile at all doses with mild local and systemic reactogenicity. Seven days after vaccination, although no significant differences were observed between the doses, OVX836 increased the frequency of nucleoprotein-specific IFNγ SFCs per million PBMCs from days 1 to 8 (primary endpoint): by 124 SFCs per 106 PMBCs (95% CI 67 to 180; p=0·002) at 180 μg; by 202 SFCs per 106 PMBCs (95% CI 138 to 267; p<0·0001) at 300 μg; by 223 SFCs per 106 PMBCs (95% CI 147 to 299; p<0·0001) at 480 μg; and decreased by 1 SFCs per 106 PMBCs (95% CI –24 to 22] in the placebo group (Kruskal-Wallis test p<0·0001 followed by Mann-Whitney's tests; per-protocol cohort). Dose-dependent and polyfunctional nucleoprotein-specific CD4 T-cell responses were observed, and CD8 T-cell responses were elicited at 300 μg and 480 μg (secondary endpoints).

Study Interpretation

OVX836 appears to be a safe and well-tolerated candidate vaccine that elicits humoral and cellular nucleoprotein-specific immune responses (including CD8 T cells at the highest dose levels) and shows a preliminary signal of protection against influenza. Therefore, OVX836 is a promising vaccine candidate for universal influenza A prevention that warrants further trials.