Osivax’s OVX836 influenza vaccine reported 24% efficacy in the Phase 2b Asuniva trial, missing its 50% target as development shifts toward combination vaccines.
Written By: Anamika Koshti, PharmD
Reviewed By: Pharmacally Editorial Team
Osivax has reported that its Phase 2b Asuniva trial of OVX836, an investigational nucleoprotein-based influenza A vaccine, failed to meet its prespecified primary efficacy target. The trial estimated vaccine efficacy (VE) at 24%, below the 50% target, without statistical significance.
Secondary efficacy estimates ranged from 25% to 28%. Osivax is now focusing development on combination vaccines through agreements with GC Biopharma and a second, undisclosed global pharmaceutical partner.
Asuniva Trial Results
Asuniva (NCT05569239) was a randomized, double-blind, placebo-controlled Phase 2b study conducted in Belgium, France, Finland and Germany. It enrolled 2,850 healthy adults aged 18–59 years who received a single 480 µg intramuscular dose of OVX836 or placebo.
The primary VE estimate was 24%, missing the prespecified 50% target. Secondary estimates were 28% against CDC-defined influenza-like illness, 27% against influenza A/H3 and 25% against A/H1N1pdm09.
Osivax also reported robust nucleoprotein-specific antibody and T-cell responses, with a safety profile consistent with earlier trials. However, the press release does not provide confidence intervals, case counts or detailed statistical analyses. The secondary findings therefore remain preliminary and do not establish clinical protection.
Earlier Phase 2a Results Were Not Reproduced
An earlier Phase 2a study (NCT05060887) reported preliminary VE of 84% against PCR-confirmed symptomatic influenza in healthy adults aged 18–55 years. Asuniva did not reproduce an efficacy estimate of comparable magnitude, although differences in study populations and endpoints limit direct comparison.
The result highlights the uncertainty of translating preliminary efficacy signals into larger field trials. Asuniva provides a more substantial test of OVX836 as a standalone vaccine, but the available results do not establish the magnitude or reliability of its protective effect.
Combination Vaccines Become the Strategic Priority
OVX836 uses Osivax’s oligoDOM platform to assemble recombinant nucleoprotein (NP), a conserved internal influenza A antigen, into self-forming nanoparticles designed to stimulate antibody and T-cell responses.
Conventional seasonal vaccines primarily target variable surface antigens, including hemagglutinin and neuraminidase. Combining OVX836 with seasonal vaccines could potentially complement strain-specific antibody protection with additional cellular immunity.
An earlier Phase 2a study (NCT05284799) evaluating OVX836 alongside a quadrivalent seasonal influenza vaccine reported no major immune interference. This supports the feasibility of co-administration but does not demonstrate improved clinical efficacy.
Osivax plans to advance combination-vaccine development with GC Biopharma and a second undisclosed global partner. Financial terms, development timelines and subsequent trial plans have not been disclosed.
Clinical Interpretation
Asuniva is a negative primary-endpoint result for OVX836 as a standalone vaccine. Although secondary efficacy estimates were directionally consistent across influenza A subtypes, their statistical uncertainty prevents firm conclusions about clinical benefit.
The combination strategy offers a potential development path alongside established seasonal vaccines, but its rationale remains unproven clinically. Asuniva did not test a combination regimen, and the earlier co-administration findings address immune responses rather than comparative protection. Controlled trials will be needed to determine whether adding OVX836 improves efficacy over seasonal vaccination alone.
References
Osivax Reports Phase 2b Results for OVX836 and Advances Combination Strategy for Next-Generation Seasonal Influenza Vaccines, Osivax, 15 October 2026
Efficacy, Immunogenicity and Safety of OVX836 Influenza Vaccine 480μg, ClinicalTrials.gov ID NCT05569239
About the Writer
Anamika Koshti (LinkedIn) is a PharmD professional and healthcare writer with interests in clinical research, pharmacovigilance, and evidence-based medicine. She has authored peer-reviewed publications on Alzheimer’s disease and PCOS, presented research at national conferences, and gained hands-on experience in medical content development and clinical data interpretation. She is committed to translating complex medical research into accurate, accessible content for healthcare professionals and patients.