Mpox in Alameda County

Mpox Updates (October 31, 2025)

Community Spread of Clade I Mpox Within California  

The California Department of Public Health (CDPH) and local health departments have identified three unrelated cases of clade I mpox among Southern California residents without a history of recent international travel, indicating that person-to-person community spread is occurring in California. Clade I mpox is different from clade II mpox, which has been circulating in California and the United States since 2022. This is the first time clade I cases without a history of international travel have been reported in California or the United States. You can prevent both Clade I and II mpox by getting the mpox vaccine (two doses of JYNNEOS). Mpox is spread through intimate contact and the risk to the general public remains low.

What people can do who may be at risk for mpox:   

• Protect yourself by getting both doses of the mpox vaccine if you or your sex partner(s) may be at risk for mpox.  Click here to find a nearby vaccine provider and get vaccinated.
• Mpox is characterized by a diffuse or localized rash. Mpox symptoms in clade I cases can be severe. The risk of severe disease and hospitalization is highest for people with weakened immune systems. Mpox may present with flu-like symptoms, followed by a rash, and are diagnosed through laboratory testing. See a provider for testing if you have a rash that may be mpox.
• If you have been exposed to mpox and not received the vaccine, the JYNNEOS vaccine (mpox vaccine) can prevent the illness if given early. (should we have them reach to us so that we can do Home PEP?)
• The vaccine is very effective!  One dose of the vaccine has 36-75% efficacy, and two doses has 66-89% efficacy for prevention of mpox (see JYNNEOS Vaccine Effectiveness).

What providers can do:  

• Test for mpox when a patient presents with new rash and other symptoms (see Compatible Signs and Symptoms).
• Recommend mpox vaccination for persons at risk, and a second dose for anyone who has not completed the 2-dose series. Getting more than 2 doses (“booster”) is not recommended. In Alameda County, anyone who thinks they need the vaccine should get it.   Click here to find a nearby vaccine provider
• Ensure persons know the signs and symptoms of mpox illness so they are evaluated and tested in a timely way if they are symptomatic.
• Submit a confidential morbidity report (CMR) to Alameda County Public Health Department for suspect and confirmed cases of mpox that reside in Alameda County.
• Ask about upcoming travel plans and recommend the mpox vaccine for individuals at risk. Click here for additional information on how to prevent mpox while traveling. Click here for additional information on how to prevent mpox while traveling.
• For persons with suspect mpox who have had recent travel to specific locations or contact with someone with known mpox clade I, test for mpox Clade I. Contact Alameda County Public Health Department at sexualhealth@acgov.org and follow the procedures for testing for Clade I mpox by sending the test to the Viral and Rickettsial Disease Laboratory (VRDL).