GeoVax Labs, Inc. (Nasdaq: GOVX) announced on September 21, 2026, the publication of preclinical research on bioRxiv demonstrating that a single dose of an enhanced Modified Vaccinia Ankara (MVA) vaccine construct, designated MVA-X, provided durable protection against lethal orthopoxvirus challenges, including highly pathogenic Clade I mpox virus. The findings, which have not yet been peer-reviewed, suggest a potential shift from the current two-dose MVA regimen for mpox prevention and could have significant implications for outbreak response and biosecurity preparedness.
The manuscript, titled “Single-dose Efficacy of a Next-Generation Mpox Vaccine Harnessing an Immunomodulatory Peptide,” reports that a single MVA-X immunization protected animals against lethal and high-dose orthopoxvirus challenge at Days 55, 90, and 150 post-vaccination, achieving protection comparable to a conventional two-dose MVA regimen. Notably, MVA-X also protected highly susceptible animals against lethal challenge with Clade I mpox virus, a strain associated with more severe disease. The research was conducted in collaboration with Washington State University and funded by GeoVax. The full preprint is available at https://www.biorxiv.org/content/10.64898/2026.07.31.742137v1.
Beyond survival, single-dose MVA-X restricted viral replication and systemic dissemination, and generated durable antigen-specific CD8+ T-cell responses even as circulating antibody levels declined. This points to a critical role for cellular immunity in controlling orthopoxvirus infection. “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,” said Mark Newman, Ph.D., Chief Scientific Officer of GeoVax.
The potential operational impact is substantial. Currently recommended MVA-based mpox vaccination generally requires two doses, which complicates deployment during outbreaks. A single-dose regimen could simplify logistics, accelerate vaccination campaigns, and reduce the burden on at-risk populations. “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,” said David Dodd, Chairman and CEO of GeoVax.
GeoVax is advancing MVA-X as part of a broader strategy to expand the utility of the MVA platform across three key areas: dosing, manufacturing, and administration. In parallel with the single-dose approach, the company is developing continuous cell-line manufacturing and evaluating needle-free microarray patch delivery. These initiatives aim to improve the operational flexibility of MVA-based vaccines, particularly in resource-constrained and biosecurity settings.
The company’s priority program, GEO-MVA, is an MVA-based vaccine targeting mpox and smallpox that is advancing under an expedited regulatory pathway, with plans to initiate a pivotal Phase 3 clinical trial in the second half of 2026. The preclinical MVA-X findings may inform that program, though the company cautions that results from animal studies may not predict human outcomes. GeoVax maintains a global intellectual property portfolio and continues to evaluate strategic partnerships. For more information, visit https://www.geovax.com.
