GEO-CM04S1 Designed to Deliver Broader, More Durable Protection for the 40 Million Americans Left Vulnerable by Limited Effectiveness of Current Vaccines

ATLANTA, GA - October 28, 2025 (NEWMEDIAWIRE) - GeoVax Labs, Inc. (Nasdaq: GOVX), a clinical-stage biotechnology company developing multi-antigen vaccines and immunotherapies for infectious diseases and cancer, today highlighted the recently issued Infectious Diseases Society of America (IDSA) guidelines recommending immediate and prioritized COVID-19 vaccination for immunocompromised individuals. The new guidelines underscore the significant unmet need in this population - one that remains at heightened risk of severe illness despite widespread vaccine availability – and confirms what clinicians, patients and policymakers have long recognized: over 40 million Americans with weakened immune systems remain at heightened risk of severe COVID-19 illness and are underserved by existing vaccines.

The IDSA guidance, published October 17, 2025, concludes that current COVID-19 vaccines offer moderate protection in immunocompromised patients, with effectiveness against hospitalization ranging from 33% to 56% and reduced - but still present - protection against critical illness and mortality. However, responses remain attenuated and short-lived, with most studies showing waning effectiveness within two months of vaccination.

GEO-CM04S1: Designed for Immunocompromised Patients

GeoVax’s GEO-CM04S1 is a multi-antigen, Modified Vaccinia Ankara (MVA)-based COVID-19 vaccine uniquely designed to stimulate both humoral (antibody) and cellular (T-cell) immunity. This broader immune activation is particularly important for immunocompromised patients - such as those undergoing chemotherapy, solid organ transplant, or receiving immunosuppressive biologics - who often fail to mount adequate antibody responses from current mRNA vaccines.

“Unlike existing vaccines that rely primarily on antibody responses, GEO-CM04S1’s multi-antigen design and proven MVA platform provide robust T-cell immunity, which is less affected by immunosuppressive conditions,” said David A. Dodd, Chairman & CEO of GeoVax. “This aligns directly with IDSA’s call for vaccine strategies tailored to patients who remain vulnerable despite vaccination.”

Clinical Progress of GEO-CM04S1

GEO-CM04S1 is currently being evaluated in multiple clinical studies among immunocompromised patients, including:

• Phase 2 trial in immunocompromised chronic lymphocytic leukemia (CLL) patients, in a direct comparison to mRNA vaccines.
• Phase 2 study in hematopoietic stem cell transplant recipients, in a direct comparison to an mRNA vaccine.

Interim results to date demonstrate durable T-cell responses, sustained neutralizing activity across emerging variants, and favorable tolerability.  In the CLL study, the mRNA vaccine arm was halted as a result of not attaining the pre-determined continuation endpoint. GEO-CM04S1 exceeded the continuation endpoint, resulting in the remainder of the study conducted only among GEO-CM04S1 recipients.

Addressing the Shortfalls of Current Vaccines

The IDSA panel emphasized that current vaccines - predominantly mRNA-based - provide incomplete and waning protection for immunocompromised individuals, especially transplant recipients and those receiving B-cell depleting therapies.

GEO-CM04S1’s structural design offers:

• Multi-antigen breadth (Spike + Nucleocapsid proteins).
• Durable cellular immunity critical for long-term protection.
• Applicability across immunocompromised subgroups where antibody-only constructs appear inadequate.

“IDSA’s updated guidance validates the path GeoVax has taken,” added Dodd. “By focusing on the needs of the over 40 million immunocompromised Americans and over 400 million worldwide, GEO-CM04S1 has the potential to fill one of the largest remaining gaps in COVID-19 protection.”

About GeoVax

GeoVax Labs, Inc. is a clinical-stage biotechnology company developing novel vaccines against infectious diseases and therapies for solid tumor cancers. The Company’s lead clinical program is GEO-CM04S1, a next-generation COVID-19 vaccine currently in three Phase 2 clinical trials, being evaluated as (1) a primary vaccine for immunocompromised patients such as those suffering from hematologic cancers and other patient populations for whom the current authorized COVID-19 vaccines are insufficient, (2) a booster vaccine in patients with chronic lymphocytic leukemia (CLL) and (3) a more robust, durable COVID-19 booster among healthy patients who previously received the mRNA vaccines. In oncology the lead clinical program is evaluating a novel oncolytic solid tumor gene-directed therapy, Gedeptin®, having recently completed a multicenter Phase 1/2 clinical trial for advanced head and neck cancers. GeoVax is also developing a vaccine targeting Mpox and smallpox and, based on recent EMA regulatory guidance, anticipates progressing directly to a Phase 3 clinical evaluation, omitting Phase 1 and Phase 2 trials. GeoVax has a strong IP portfolio in support of its technologies and product candidates, holding worldwide rights for its technologies and products. For more information about the current status of our clinical trials and other updates, visit our website: www.geovax.com.

Forward-Looking Statements

This release contains forward-looking statements regarding GeoVax’s business plans. The words “believe,” “look forward to,” “may,” “estimate,” “continue,” “anticipate,” “intend,” “should,” “plan,” “could,” “target,” “potential,” “is likely,” “will,” “expect” and similar expressions, as they relate to us, are intended to identify forward-looking statements. We have based these forward-looking statements largely on our current expectations and projections about future events and financial trends that we believe may affect our financial condition, results of operations, business strategy and financial needs. Actual results may differ materially from those included in these statements due to a variety of factors, including whether: GeoVax is able to obtain acceptable results from ongoing or future clinical trials of its investigational products, GeoVax’s immuno-oncology products and preventative vaccines can provoke the desired responses, and those products or vaccines can be used effectively, GeoVax’s viral vector technology adequately amplifies immune responses to cancer antigens, GeoVax can develop and manufacture its immuno-oncology products and preventative vaccines with the desired characteristics in a timely manner, GeoVax’s immuno-oncology products and preventative vaccines will be safe for human use, GeoVax’s vaccines will effectively prevent targeted infections in humans, GeoVax’s immuno-oncology products and preventative vaccines will receive regulatory approvals necessary to be licensed and marketed, GeoVax raises required capital to complete development, there is development of competitive products that may be more effective or easier to use than GeoVax’s products, GeoVax will be able to enter into favorable manufacturing and distribution agreements, and other factors, over which GeoVax has no control.

Further information on our risk factors is contained in our periodic reports on Form 10-Q and Form 10-K that we have filed and will file with the SEC. Any forward-looking statement made by us herein speaks only as of the date on which it is made. Factors or events that could cause our actual results to differ may emerge from time to time, and it is not possible for us to predict all of them. We undertake no obligation to publicly update any forward-looking statement, whether as a result of new information, future developments or otherwise, except as may be required by law.

Company Contact:
info@geovax.com
678-384-7220

Media Contact:
Jessica Starman
media@geovax.com