San Francisco reports first case of severe mpox strain

Key Points:

• San Francisco public health officials confirmed the city's first case of clade I mpox, a strain potentially causing more severe illness than the clade II strain responsible for the 2022 outbreak; the patient, an unvaccinated adult, was hospitalized but is now improving.
• Clade I mpox cases remain rare in the U.S., with only 15 reported as of March, but health officials emphasize the importance of full vaccination, especially for those at higher risk, ahead of summer travel and events.
• The two-dose Jynneos vaccine offers protection against both clade I and clade II mpox strains, and residents can access vaccination through healthcare providers, pharmacies, or city resources, with no need to restart the vaccine series if the second dose is delayed.
• Mpox primarily spreads through close skin-to-skin contact, including sexual contact, with most U.S. cases reported among gay, bisexual, and transgender men who have sex with men; anyone with a rash resembling mpox is urged to seek medical testing and notify partners.
• San Francisco joins a short list of U.S. jurisdictions reporting clade I infections, following earlier cases in California, including one in Los Angeles County with no recent travel history to endemic regions.