A colorized transmission electron micrograph of mpox virus particles (pink) found within an infected cell (green), cultured in the laboratory.

California health officials are encouraging at-risk individuals to receive the mpox vaccine as cases rise in the state, the California Department of Public Health announced this month. 

San Francisco’s first case of clade I mpox was identified earlier in April, CDPH said, making it the seventh identified case of clade I mpox in California since November 2024. Meanwhile, cases of the other, less severe strain, clade II, are steadily increasing.

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“So far in 2026, California is experiencing more than double the average weekly number of clade II cases compared to the same period in previous years — 14.5 weekly cases in 2026 compared to 5.8 in 2024 and 3.4 in 2025,” an April 17 California Department of Public Health news........

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