The U.S. Centers for Disease Control and Prevention (CDC) has reported a significant shift in the epidemiology of Clade I mpox in the United States. In its September 25 update, the CDC confirmed more than 60 laboratory-confirmed Clade I mpox cases across at least 20 states. Notably, since August, an increasing proportion of these cases have occurred among individuals with no recent international travel or known links to travelers. Cases with presumed domestic transmission have now been reported in more than 10 jurisdictions, leading the CDC to state that this indicates a “likely transition to sustained Clade Ib transmission in the United States.” While the CDC continues to assess the risk from the Clade I outbreak as low for most people in the United States, it notes that additional travel-related and domestically acquired Clade Ib cases are expected.
GeoVax Labs, Inc. (Nasdaq: GOVX), a clinical-stage biotechnology company developing vaccines against infectious diseases and therapies for solid tumor cancers, highlighted this development. David Dodd, Chairman and CEO of GeoVax, commented, “CDC’s latest assessment represents an important change in the epidemiology of Clade Ib mpox in the United States. While the risk to the general population remains low, presumed domestic transmission across multiple jurisdictions reinforces the importance of continued surveillance, vaccination of appropriate at-risk populations and sustained preparedness.” Dodd continued, “Preparedness should not begin when an infectious-disease threat becomes a crisis. The appropriate time to strengthen vaccine capacity, diversify sources of supply and establish scalable manufacturing infrastructure is before those capabilities are urgently needed. The changing geographic footprint and public health threat of mpox is another reminder that infectious diseases do not respect national borders.”
In response to this evolving landscape, GeoVax is advancing GEO-MVA, its Modified Vaccinia Ankara (MVA)-based vaccine candidate for protection against mpox and smallpox. Following formal guidance from the European Medicines Agency (EMA), GeoVax is progressing GEO-MVA through an expedited clinical development pathway, with traditional Phase 1 and Phase 2 trials not required. This allows the program to proceed directly to a pivotal Phase 3 immunobridging study comparing immune responses generated by GEO-MVA with those of the licensed MVA-BN comparator. GeoVax expects to initiate the 500-participant pivotal Phase 3 study in the fourth quarter of 2026, with results expected in mid-2027. The company has completed the manufacturing/fill-finish and clinical operations aspects necessary to support the initiation and completion of the study.
GeoVax is developing GEO-MVA to expand global access to MVA vaccines and scalable production capabilities, with the potential to provide governments and international public health organizations with an additional source of MVA vaccine. The company believes GEO-MVA can become an important strategic preparedness asset by supporting diversified vaccine supply, scalable manufacturing capacity, and greater supply resilience, while strengthening biosecurity, orthopoxvirus preparedness, and the ability to respond to evolving global health threats. Dodd concluded, “Low risk to the general population today and the need for long-term preparedness are not contradictory. CDC’s latest assessment illustrates why preparedness must anticipate changes in infectious-disease transmission rather than react to them after they occur. We believe diversified vaccine supply and scalable MVA manufacturing capacity can become increasingly important as the epidemiology of mpox continues to evolve.”
The changing mpox landscape is particularly noteworthy because the 2022 global outbreak, including the large U.S. outbreak, was caused by Clade IIb. Clade I mpox has historically been associated with more severe disease and higher mortality than Clade II, though severity varies by subclade, population, and access to medical care. Recent Clade Ib cases in high-income countries have generally involved relatively mild illness, underscoring the importance of distinguishing the changing epidemiology from the immediate risk to the general population. The CDC’s latest assessment represents an evolution from earlier surveillance; as recently as August, the CDC reported that sustained Clade Ib transmission had not been detected in the United States during 2024–2025. Globally, Clade I outbreaks have continued in Central and Eastern Africa since late 2023, with subsequent geographic expansion, including transmission in parts of Europe and introductions into the United States. This evolving situation follows other public-health preparedness actions, such as updated CDC vaccination recommendations for certain travelers and international initiatives to strengthen access to mpox vaccines and outbreak-response capabilities. For more information about GeoVax, visit www.geovax.com.
This news matters because it signals a potential shift in mpox transmission dynamics within the United States, which could have implications for public health preparedness and vaccine supply. As the virus becomes established domestically, the need for robust surveillance, vaccination strategies, and diversified vaccine manufacturing becomes more urgent. GeoVax’s advancement of GEO-MVA could contribute to global preparedness efforts, offering an additional vaccine option and scalable production capacity to address current and future outbreaks. The development underscores the importance of proactive measures in infectious disease control, as highlighted by the NEWMEDIAWIRE release.
