Why Did GeoVax Labs Stock Soar 17.78%? Positive Vaccine Data, Regulatory Boost

On June 19, 2025, GeoVax Labs' stock price surged by 17.78% in pre-market trading, marking a significant rise that has captured the attention of investors and analysts alike.

GeoVax Labs recently presented positive immune response results from its GEO-CM04S1 vaccine at the European Hematology Association 2025 Meeting. The data highlighted the superior T cell responses induced by GEO-CM04S1 compared to an authorized mRNA-based COVID-19 vaccine in patients with chronic lymphocytic leukemia (CLL). This is particularly significant as CLL patients often exhibit suboptimal protective responses to vaccines due to immune dysfunction.

The study demonstrated that GEO-CM04S1 elicited statistically significant SARS-CoV-2 Nucleocapsid (N)-specific IgG and T cell responses, while the mRNA vaccine failed to meet the pre-defined primary immunogenicity endpoint. Both vaccines were well-tolerated, with no grade ≥3 adverse events reported. These findings underscore the potential of GeoVax's multi-antigen approach in providing broader and more durable immunity against COVID-19.

Additionally, GeoVax Labs received favorable regulatory feedback from European authorities, confirming that a single Phase 3 immuno-bridging trial would be sufficient to evaluate the efficacy and support a Marketing Authorization Application (MAA) for vaccination. This regulatory clarity is expected to accelerate the company's path to market approval and further boost investor confidence.