GeoVax Vaccine Data Aligns With IDSA Guidance for Protecting Immunocompromised Patients

New clinical data from GeoVax Labs' COVID-19 vaccine candidate GEO-CM04S1 aligns with recently updated Infectious Diseases Society of America guidelines highlighting the urgent need for better protection for immunocompromised patients. The IDSA guidance, issued October 17, 2025, concluded that existing COVID-19 vaccines provide only moderate and short-lived protection for immunocompromised patients, with effectiveness against hospitalization ranging from 33% to 56% and waning within two months.

The panel specifically called for new vaccine strategies tailored to vulnerable populations, including cancer patients, transplant recipients, and individuals receiving immunosuppressive therapies. David A. Dodd, Chairman & CEO of GeoVax, emphasized that immunocompromised Americans represent one in eight adults and include cancer patients, transplant recipients, people with autoimmune disease, and those living with HIV. He noted that mainstream vaccine approaches, heavily centered on mRNA, continue to leave these populations without durable protection.

At the World Vaccine Congress Europe 2025 in Amsterdam, GeoVax presented interim data from ongoing Phase 2 studies of GEO-CM04S1, the company's multi-antigen, MVA-based COVID-19 vaccine designed specifically for immunocompromised populations. Key findings included robust T-cell responses to both Spike and Nucleocapsid antigens that exceeded responses seen with mRNA boosters, broad cross-variant immunity including activity against Omicron subvariants, and a favorable safety profile with only mild-to-moderate adverse events.

The data showed that in patients with hematologic malignancies post-transplant or CAR-T therapy, breakthrough infections were mild-to-moderate, underscoring the vaccine's protective potential in highly vulnerable groups. Dodd stated that these results, together with IDSA's updated guidance, reinforce the critical need for vaccine platforms that move beyond antibody-only strategies. GEO-CM04S1 is designed to provide balanced immunity - antibodies plus durable T-cell responses - which are essential for immunocompromised patients who remain most vulnerable despite existing vaccination campaigns.

GEO-CM04S1 represents a multi-antigen, Modified Vaccinia Ankara-based COVID-19 vaccine designed to elicit both antibody and T-cell immune responses. This dual-pathway activation is particularly important for patients who often fail to mount sufficient antibody responses with current mRNA vaccines. Key features include multi-antigen breadth covering both Spike and Nucleocapsid proteins, durable cellular immunity critical where antibody responses are weak, and alignment with IDSA priorities for transplant, cancer, autoimmune, and HIV patients.

Ongoing trials include Phase 2 studies as a primary vaccine for immunocompromised individuals, including post-transplant and hematologic cancer patients, and as a booster for patients with chronic lymphocytic leukemia. Interim results across these studies consistently demonstrate that GEO-CM04S1 can generate broader, more durable protection than mRNA vaccines while maintaining a strong safety profile. For more information about the current status of clinical trials and other updates, visit the company website at https://www.geovax.com.

The convergence of IDSA guidelines and clinical findings underscores how multi-antigen, T-cell-driven approaches can better protect high-risk populations and strengthen pandemic preparedness. While mRNA vaccines were pivotal in the early pandemic response, their limitations in durability, breadth, and performance in immunocompromised populations highlight the risks of relying on a single platform. Protecting the over 40 million immunocompromised Americans represents both a healthcare imperative and national security necessity, with positive clinical data and alignment with professional guidelines pointing toward potential solutions for this vulnerable population.