Recent California mpox cases spur vaccine push for high-risk people
October 29, 2025
California’s first locally acquired cases of clade I mpox mark a critical juncture in U.S. public health preparedness. Unlike the 2022 outbreak strain, clade I causes more severe illness, and all recent infections occurred in unvaccinated individuals. Health officials, led by Dr. Erica Pan, are urging high-risk communities—particularly men who have sex with men and those eligible for PrEP—to complete both doses of the Jynneos vaccine. While there is no evidence of widespread transmission, the emergence of community-acquired cases underscores an urgent need for vigilance, vaccination, and proactive outreach to prevent further spread of this more virulent mpox strain.
California health officials have issued a stark reminder about the enduring threat of mpox, after confirming the first locally acquired cases of clade I mpox in the United States. The three unrelated infections—all among unvaccinated individuals in Southern California—signal that the more virulent strain, previously confined to regions of Africa and the Middle East, has now reached American soil. Clade I mpox causes more severe symptoms than clade II, the variant responsible for the 2022 global outbreak.
Dr. Erica Pan, California’s Public Health Officer, emphasized that this development marks a turning point: “Clade I is here, it’s circulating, and people should get up to date on the vaccine.” Her warning comes as many in high-risk groups remain only partially vaccinated—having received one dose of the two-dose Jynneos series. State health agencies are now urging medical providers to proactively contact patients to ensure vaccination completion, which remains the most effective defense against serious illness.
Although no secondary cases have been detected, the emergence of community transmission is a reminder that vigilance must not wane. High-risk individuals—including men who have sex with men, people living with HIV, those eligible for PrEP or doxy PEP, and travelers to areas where mpox is endemic—should prioritize full vaccination.
Public health messaging must balance urgency with reassurance: while mpox is not exclusively a sexually transmitted infection, its primary mode of transmission—close skin-to-skin contact—requires targeted education within sexual health contexts.
California’s swift response demonstrates the value of early detection and transparent communication. But preventing broader spread will depend on personal responsibility, sustained vaccine access, and consistent outreach. The lesson from 2022 is clear—proactive vaccination and informed communities remain the cornerstone of mpox control, no matter the strain.