Osivax Reports Phase 2b Results for OVX836 Flu Vaccine

LYON, France, and LIÈGE, Belgium, October 15, 2026

Phase 2b Trial Reports Efficacy Signal but Misses Primary Endpoint

The Phase 2b OVX836-005, also known as the Asuniva trial, was a randomized, double-blind, placebo-controlled, multicenter study conducted in Belgium, France, Finland and Germany. It evaluated the safety, immunogenicity and efficacy of a single intramuscular dose of OVX836 at 480 µg in adults aged 18–59. The trial enrolled 2,850 participants and was designed to generate clinical evidence to guide the candidate’s potential advancement toward late-stage development. The study did not achieve its prespecified primary endpoint of 50% vaccine efficacy. The observed vaccine efficacy point estimate was 24% and was not statistically significant. Secondary endpoint analyses reported point estimates of 28% against CDC-defined influenza-like illness, 27% against influenza A/H3 and 25% against influenza A/H1N1pdm09. These findings provide preliminary efficacy observations but do not establish statistically significant protection. Osivax also reported robust nucleoprotein-specific antibody and T-cell responses and a safety profile consistent with earlier clinical trials. According to the company, the consistency of the efficacy point estimates across the two major influenza A subtypes represents an important research observation for a monovalent vaccine targeting an internal viral protein. The findings nevertheless need to be interpreted in the context of the missed primary endpoint and the nonsignificant overall efficacy estimate. The company has indicated that the data will inform the next phase of its influenza vaccine development strategy.

Combination Strategy Targets Broader Influenza Protection

Osivax is advancing a strategy to combine OVX836 with conventional seasonal influenza vaccines rather than relying exclusively on the investigational candidate as a standalone vaccine. Traditional seasonal vaccines provide strain-specific protection through immune responses directed at influenza antigens, while OVX836 is designed to generate broader cellular immunity by targeting the virus’s nucleoprotein (NP). The NP is an internal viral antigen that is more conserved than surface antigens, making it a potential target for immune responses that could extend across multiple influenza A strains. Osivax uses its proprietary oligoDOM™ technology to produce a recombinant form of NP that self-assembles into nanoparticles and is designed to stimulate both T-cell and B-cell responses. The company believes combining these immune mechanisms could complement the protection provided by existing seasonal vaccines and potentially improve overall vaccine efficacy. Osivax recently established collaborations with GC Biopharma and a second, undisclosed global pharmaceutical partner to support development of combination vaccine candidates administered in a single injection. The agreements provide access to established seasonal influenza vaccines for combination development. Osivax Chief Medical Officer Nicola Groth said the consistency of the observed efficacy signal across influenza A subtypes, together with the immunogenicity and safety findings, supports further investigation of nucleoprotein-targeted immunity as a complementary mechanism. Chief Executive Officer and Co-Founder Alexandre Le Vert said the company sees an opportunity to combine strain-specific antibody protection with broader cellular immune responses. The potential benefits of these combinations will need to be demonstrated in subsequent studies.

Development Outlook and Next Steps

OVX836 has been evaluated in seven clinical trials involving more than 4,000 participants, according to Osivax. The company is developing the candidate as a broad-spectrum influenza A vaccine and intends to use the Phase 2b results to guide its next development decisions. The combination approach represents a strategic shift in emphasis toward pairing OVX836 with existing seasonal vaccines, with the goal of broadening protection rather than replacing current formulations. The two pharmaceutical collaborations are expected to support development of single-injection combination candidates, although the announcement did not disclose specific development timelines, trial designs or anticipated regulatory milestones for these programs. Osivax also reports collaborations with global health organizations, including the U.S. Biomedical Advanced Research and Development Authority (BARDA) and the National Institutes of Health (NIH), as well as European institutions and pharmaceutical companies. The company’s broader platform is intended to generate strong T-cell responses alongside sustained B-cell responses and may be applied to other infectious disease indications through future collaborations. The Phase 2b findings offer data to support continued investigation of the approach, but the missed primary endpoint means the results do not establish the intended 50% efficacy target for OVX836 as a standalone vaccine. Further clinical studies will be needed to assess whether a combination formulation can provide improved protection, demonstrate an acceptable safety profile and support advancement toward later-stage development.

Source::Osivax press release