GeoVax Labs, Inc. (Nasdaq: GOVX) announced the publication of preclinical research on bioRxiv demonstrating that a single dose of an enhanced Modified Vaccinia Ankara (MVA) vaccine, designated MVA-X, provides durable protection against lethal orthopoxvirus challenges, including highly pathogenic Clade I mpox virus. The findings, if translated to humans, could significantly alter vaccination strategies for mpox and other orthopoxvirus threats by reducing the need for a two-dose regimen.
The study, titled “Single-dose Efficacy of a Next-Generation Mpox Vaccine Harnessing an Immunomodulatory Peptide,” was conducted in collaboration with Washington State University and funded by GeoVax. It reports that a single MVA-X vaccination protected against lethal and high-dose orthopoxvirus challenges at Days 55, 90, and 150 post-vaccination, achieving protection comparable to a conventional two-dose MVA regimen. Importantly, MVA-X also protected highly susceptible animals against lethal Clade I mpox virus, a strain associated with more severe disease.
MVA has a long safety record and is a critical platform for biosecurity and outbreak preparedness. Current mpox vaccination typically requires two doses, which complicates deployment during outbreaks, especially in resource-limited settings. MVA-X was engineered to enhance early immune priming, potentially enabling durable protection from a single shot. The research showed that MVA-X restricted viral replication and systemic dissemination, and generated durable antigen-specific CD8+ T-cell responses even as circulating antibody levels declined, underscoring the role of cellular immunity in controlling orthopoxvirus infection.
David Dodd, Chairman and CEO of GeoVax, commented, “Two-dose administration has long been an accepted characteristic of MVA vaccination. These results provide encouraging preclinical evidence that it may be possible to achieve durable protection following a single vaccination utilizing MVA-X. During an outbreak, reducing a two-dose regimen to a single vaccination could simplify deployment, accelerate completion of vaccination programs and reduce the logistical burden associated with protecting at-risk populations.”
Mark Newman, Ph.D., Chief Scientific Officer of GeoVax, added, “These data point toward an innovative approach to augmenting MVA potency and provide support for the important role of the cellular arm of the immune system, particularly CD8-positive T-cell responses, in controlling and clearing orthopoxvirus infection.”
The MVA-X research is part of a broader GeoVax strategy to expand the utility of the MVA platform. In addition to improving immunogenicity for single-dose regimens, GeoVax is advancing continuous cell-line manufacturing and evaluating needle-free microarray patch delivery. These initiatives address dosing, manufacturing, and administration challenges, aiming to make MVA-based vaccines more practical for global health, outbreak response, and biosecurity.
The manuscript is available as a preprint on bioRxiv under DOI 10.64898/2026.07.31.742137. It has not been peer-reviewed, and preclinical results may not predict human outcomes. GeoVax’s lead program, GEO-MVA, is advancing under an expedited regulatory pathway with a planned pivotal Phase 3 trial in the second half of 2026. For more information, visit www.geovax.com.
