GeoVax Labs, Inc. presented interim clinical data for its multi-antigen COVID-19 vaccine candidate GEO-CM04S1 at the World Vaccine Congress Europe 2025, showing promising results for immunocompromised patient populations. The presentations highlighted the vaccine's ability to generate robust T-cell responses and maintain a favorable safety profile in vulnerable individuals who often respond poorly to conventional vaccines.
Chief Scientific Officer Mark J. Newman, PhD, presented Phase 2 data demonstrating that GEO-CM04S1 elicits strong T-cell responses to both Spike (S) and Nucleocapsid (N) antigens, exceeding responses induced by mRNA boosters. The workshop presentation emphasized limitations of current "one-size-fits-all" vaccines for immunocompromised populations and showed GEO-CM04S1's potential to provide broader, more durable protection against COVID-19 variants. Preclinical and early clinical data indicated responses against Omicron subvariants, suggesting the vaccine could reduce the need for frequent reformulations.
Chief Medical Officer Kelly T. McKee, Jr., MD, MPH presented interim safety results from a Phase 2 trial involving patients with hematologic malignancies who had received hematopoietic stem cell transplants or chimeric antigen receptor (CAR)-T cell therapy. The data showed GEO-CM04S1 maintained a safety profile comparable to mRNA vaccines, with only mild-to-moderate treatment-emergent adverse events primarily consisting of injection site reactions, fatigue, and myalgia. Importantly, no vaccine-related serious adverse events, myocarditis, or pericarditis were reported, and breakthrough infections that occurred were mild-to-moderate in severity.
David Dodd, Chairman and CEO of GeoVax, stated these findings support the company's conviction that GEO-CM04S1 could fill a critical gap for immunocompromised patients inadequately protected by existing vaccines. The synthetic, next-generation vaccine candidate uses GeoVax's MVA vector platform to co-express spike and nucleocapsid antigens, designed to induce both antibody and T-cell responses. GEO-CM04S1 is currently being evaluated in three Phase 2 clinical trials: as a primary vaccine for immunocompromised individuals, as a booster for patients with chronic lymphocytic leukemia, and as a durable booster for healthy adults previously immunized with mRNA vaccines.
The implications of these findings are significant for global public health, as immunocompromised individuals represent a population particularly vulnerable to severe COVID-19 outcomes. Current vaccines often provide suboptimal protection for these patients, creating a persistent risk group in pandemic management. The demonstrated safety profile and robust immune responses suggest GEO-CM04S1 could potentially reduce hospitalizations and severe illness in these high-risk populations. For more information about GeoVax's clinical programs and technology platform, visit https://www.geovax.com.
