San Francisco has logged its first confirmed case of clade I mpox, a version of the virus that federal experts say can cause more severe illness than the strain behind the 2022 outbreak. The patient is an unvaccinated adult who was hospitalized after what officials describe as close contact with someone who had recently traveled abroad. The person is now improving, and city health leaders say the overall public risk is still low, although they are urging people at higher risk to finish the two-dose mpox vaccine series ahead of summer trips and big events.
The San Francisco Department of Public Health confirmed the case after the patient reported close contact with an international traveler, according to the San Francisco Chronicle. Health Officer Dr. Susan Philip underscored that being fully vaccinated remains the strongest protection against serious illness.
Federal officials say clade I has historically been linked to more severe disease, and the Centers for Disease Control and Prevention reported that 15 clade I cases had been identified nationwide through March. Most of those patients were recovering, the agency said, while federal and state teams continue to track the virus's spread. The CDC describes the overall risk to most Americans as low, and the risk to men who have sex with men as low to moderate.
City health officials reiterated that the two-dose JYNNEOS vaccine protects against both clade I and clade II mpox and can lower the chance of severe illness and hospitalization. People who received only the first dose do not need to restart the series, even if more than 28 days have passed, according to the city’s current guidance. Officials also pointed out that antiviral medications are available for more serious cases and that quick testing and early treatment can improve outcomes.
How to Protect Yourself and Where to Get Vaccinated
Public health officials advise anyone who develops a new rash, blisters, or flu-like symptoms to contact a health care provider for testing and to alert recent partners so they can be evaluated as well. Vaccines are offered through health systems, community clinics, and pharmacies, and people who are uninsured or unsure where to go can turn to the city’s mpox resource pages and related local information to find a site.
The San Francisco case comes after earlier clade I detections in California, including a travel-associated diagnosis in San Mateo County in late 2024. For now, state and federal officials say community spread in the United States has remained limited. Health departments are continuing to sequence samples and conduct contact tracing to better understand transmission and identify clusters as early as possible.
SFDPH said it is still investigating potential contacts and will update the public as needed. Residents who have questions about symptoms, testing, or vaccination can check with local clinics and review the city’s mpox web pages for current guidance and clinic schedules.
