Why new mpox cases in California are raising concerns
October 26, 2025
California’s detection of three clade I mpox cases—the first community-acquired infections of this more virulent strain in the U.S.—signals a troubling shift in the country’s post-outbreak landscape. Clade I, historically linked to higher mortality and transmissibility in Central Africa, has now surfaced domestically among unvaccinated individuals requiring hospitalization. Experts warn that underfunded federal infrastructure and a government shutdown may limit effective monitoring and coordination, leaving state health agencies to shoulder the burden. While the public risk remains low, the emergence of local transmission underscores how fragile progress can be when political instability undermines public health readiness and surveillance capacity.
More than two years after the 2022 mpox outbreak was declared over, California’s detection of three unrelated clade I mpox cases has reignited concern among infectious disease experts. The infections—requiring hospitalization and unconnected to international travel—suggest community spread of a more severe, more transmissible strain historically associated with higher mortality in Central Africa.
Experts like Dr. Joseph Cherabie warn that this represents a shift from isolated importation to potential local circulation. Clade I mpox poses greater risks than the clade II strain that drove the 2022 global outbreak, though, reassuringly, no deaths have been reported in California. The state’s Department of Public Health maintains that the overall risk to the general public remains low, emphasizing that mpox transmission occurs primarily through close, often intimate contact, rather than casual exposure.
Still, the situation highlights deeper structural vulnerabilities. Federal public health capacity has been strained by layoffs, communication restrictions, and the current government shutdown, weakening coordination and data-sharing between state and national agencies. As Dr. Cherabie noted, “Our ability to monitor and test… has been massively eviscerated by the public health cutbacks.” In such a context, California’s robust state response stands out as a critical line of defense.
Fortunately, the tools to contain mpox remain available: the Jynneos smallpox vaccine and the antiviral TPOXX (tecovirimat) have both proven effective against clade I and clade II strains. Ensuring access to these countermeasures—and rebuilding the national infrastructure needed to track and respond to outbreaks—is essential.
California’s new cases serve as both a warning and an opportunity: a warning that complacency and political neglect can erase hard-won gains, and an opportunity to reaffirm that public health is only as strong as the systems and leadership that sustain it.