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Erica Pan, MD, MPH
State Public Health Officer & Director
Gavin Newsom
Governor State of California—Health and Human Services Agency
California Department of Public Health
Health Advisory
TO: Healthcare Providers
Recent Rise of Mpox Cases in California and the Bay Area
8/26/2025
Key Messages
- The California Department of Public Health (CDPH) is reporting an increase in clade II mpox cases in California during July and August 2025, predominantly in the San Francisco Bay Area.
- As a reminder, mpox testing should be considered for sexually active patients with compatible signs and symptoms (PDF), regardless of vaccination status or previous infection.
- Mpox vaccination is recommended for individuals who may be at risk for mpox to prevent severe illness, need for hospitalization, and death. This includes patients who still need second doses or who may not have received vaccine at the start of the 2022 outbreak.
- Boosters (third doses) are not recommended at this time.
- Vaccines are available at many chain pharmacies and certain clinics—see Mpox Vaccine Locator.
- Incorporate assessments for mpox risk and vaccination status at all routine sexual health visits, particularly for individuals who are gay, bisexual, transgender, or other men who have sex with men.
In August 2025, so far, there has been an average of 13 clade II mpox cases per week (compared to 7.9 and 4.0 cases per week in July and June, respectively). While this increase has mostly occurred in the San Francisco Bay Area, travel between counties and sexual exposure associated with attending clubs, venues, parties, or other events is common. Most cases have been among gay, bisexual, and other men who have sex with men and their social networks. All of these cases have been clade II mpox, which has been circulating in California since 2022.
As a reminder, there are currently ongoing outbreaks of clade I mpox in sub-Saharan Africa. Sporadic travel-associated cases have since been identified in the U.S. and other countries. At this time, people who have traveled to countries with clade I mpox outbreaks and their close contacts are most at risk. All of the mpox cases in California in 2025 so far have been clade II.
Recommendations
Given this recent increase in cases, providers are reminded to incorporate mpox evaluation and prevention into routine sexual health care, including when people are being tested for sexually transmitted infections (STIs) or receiving HIV pre-exposure prophylaxis (PrEP) or post-exposure prophylaxis (PEP), doxy PEP, or treatment for HIV and other STIs.
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Mpox in Alameda County
Information on Mpox
Mpox Updates (September 3, 2025)
There has been a recent increase in mpox in Alameda County, as well as other areas in the San Francisco Bay Area (see CDPH Health Advisory). In Alameda County, we have had a 4-fold increase in mpox cases since July 2025.
Mpox is characterized by a diffuse or localized rash; the rash can be preceded by a prodrome or other symptoms in some people (see CDC Clinical Features of Mpox). Mpox is usually transmitted by close and sustained physical contact. Mpox has two clades, Clade II was the cause of the large global outbreak in 2022, and is still circulating. Clade I mpox is primarily occurring outside the United States. Both clades are prevented by JYNNEOS vaccine (mpox vaccine). One dose of the vaccine has 36-75% efficacy, and two doses has 66-89% efficacy for prevention of mpox (see JYNNEOS Vaccine Effectiveness).
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