Rare Mpox Strain Detected In San Francisco
- Health officials report a rare mpox strain has been detected in San Francisco, and cases are rising statewide. - Officials are urging Californians to get vaccinated to curb spread and protect high-risk communities. - The development could prompt expanded vaccination and surveillance efforts, public-health leaders warn (patch.com).
San Francisco has confirmed its first clade I mpox case, a rarer strain than the one behind the city’s 2022 outbreak. (sf.gov) The case was confirmed on April 14, 2026, in an unvaccinated adult who was hospitalized and is now improving, according to the San Francisco Department of Public Health. The patient reported close contact with someone who had traveled internationally to an area where clade I mpox is circulating. (sf.gov) Mpox is a viral disease that usually spreads through close skin-to-skin contact, including sexual contact, and it can start with fever, swollen lymph nodes, or fatigue before a rash appears. San Francisco officials said both clade I and clade II cause similar symptoms, but clade I cases remain rare in the United States. (sf.gov) The strain matters because the 2022 outbreak in California was driven by clade II, while clade I has been tied to a separate outbreak in Central and Eastern Africa since 2023. The Centers for Disease Control and Prevention said the risk to most people in the United States remains low, but it has logged 16 clade I cases nationwide since November 2024, including five reported since March 2026. (cdc.gov) California is also seeing ongoing mpox transmission from the older clade II strain. The California Department of Public Health says mpox has continued circulating in the state since 2022, and its statewide dashboard was refreshed on April 10, 2026. (cdph.ca.gov) State and city officials are now pushing vaccination, especially for people at higher risk. California recommends the two-dose JYNNEOS vaccine for gay and bisexual men, transgender and nonbinary people, people with HIV or on HIV prevention medicines, recent contacts of mpox cases, some travelers, and certain lab workers. (cdph.ca.gov) The federal guidance is similar and stresses finishing the full series. The Centers for Disease Control and Prevention says JYNNEOS is given in two doses, four weeks apart, and people who are late on dose two should get it as soon as possible rather than restart the series. (cdc.gov) San Francisco officials said exposure risk is still low for people outside higher-risk groups, but they are urging people at risk to get both shots before summer travel and large events. The city says vaccine is available through health care providers, pharmacies, and local public-health sites. (sf.gov)
