FAQ: GeoVax's GEO-CM04S1 Vaccine and IDSA Guidance for Immunocompromised Patients

What is the main topic of this announcement?

GeoVax is highlighting how its Phase 2 clinical data for GEO-CM04S1 vaccine aligns with new IDSA guidelines that prioritize COVID-19 vaccination for immunocompromised individuals who receive limited protection from current vaccines.

Why is this development significant for immunocompromised patients?

The IDSA guidance found existing COVID-19 vaccines provide only moderate, short-lived protection (33-56% effectiveness against hospitalization waning within two months) for immunocompromised patients, creating an urgent need for better alternatives like GEO-CM04S1.

What are the key findings from GeoVax’s Phase 2 clinical data?

Key findings include robust T-cell responses to both Spike and Nucleocapsid antigens exceeding mRNA boosters, broad cross-variant immunity including against Omicron subvariants, favorable safety profile with only mild-to-moderate adverse events, and mild-to-moderate breakthrough infections in highly vulnerable patients.

How does GEO-CM04S1 differ from current COVID-19 vaccines?

GEO-CM04S1 is a multi-antigen, MVA-based vaccine designed to elicit both antibody and T-cell immune responses, providing balanced immunity that’s particularly important for immunocompromised patients who often fail to mount sufficient antibody responses with mRNA vaccines.

Who are the immunocompromised patients this targets?

This includes cancer patients, transplant recipients, individuals with autoimmune diseases, people living with HIV, and those receiving immunosuppressive therapies - representing approximately one in eight adults according to GeoVax.

When were the IDSA guidelines and clinical data presented?

The IDSA guidance was issued on October 17, 2025, and GeoVax presented its Phase 2 interim data at the World Vaccine Congress Europe 2025 in Amsterdam, with this announcement made on October 29, 2025.

What safety profile was reported for GEO-CM04S1?

The vaccine showed a favorable safety profile with only mild-to-moderate adverse events such as injection site reactions, fatigue, and myalgia, with no vaccine-related serious adverse events reported.

Why are T-cell responses important for immunocompromised patients?

T-cell responses are essential because immunocompromised patients often cannot generate sufficient antibody protection with current vaccines, and durable T-cell immunity provides broader, longer-lasting protection that’s critical for this vulnerable population.

What is the significance of GEO-CM04S1’s multi-antigen design?

The multi-antigen design targeting both Spike and Nucleocapsid proteins provides broader immunologic coverage and is intended to generate more comprehensive protection against COVID-19 variants compared to single-antigen approaches.