Mpox (formerly monkeypox) is rising in California in 2025. Get 5 urgent updates to California Mpox cases trends, new strains, risk groups, prevention, and what the CDPH says. Stay informed and safe.
Mpox is active again in California.
In 2025, health officials are seeing new patterns and risks.
This article gives you five urgent updates.
You’ll learn about case counts, new strains, prevention, and outlook.
Everything is in easy English, with bold key terms for clarity.
Table of Contents
1. Rising Case Counts in California in 2025
The California Department of Public Health (CDPH) has reported an increase in clade II mpox cases during July and August 2025, especially in the San Francisco Bay Area.
On average, the state saw 13 new cases per week in August, up from 7.9 per week in July and 4.0 per week in June.
These rise patterns suggest local spread, travel, and social networks are contributing.
2. Detection of Clade I Strain in California
In November 2024, California confirmed the first U.S. case of clade I mpox.
This strain is more common in Central and East Africa and may cause more severe disease historically.
The patient had traveled recently from Africa. Thankfully, risk to the broader public remains low, and no known spread from this case has been confirmed.
So, California now monitors both clade II (ongoing) and the newer clade I strain.
3. Characteristics & Clinical Trends in California
A study on mpox cases in California between May 2022 to August 2024 gives insight into prolonged infections and risk factors.
- 6,469 cases were reported in that period.
- Most patients were men (≈94%) and many identified as gay, bisexual, or same-gender loving.
- Prolonged mpox infection (lasting over 28 days) occurred in 82 cases.
- Prolonged cases were more likely among those with HIV, experiencing homelessness, or Black/African American descent.
- Vaccination history mattered: very few prolonged cases had full two-dose vaccination.
This data helps underline which populations are at higher risk in California.
4. Prevention Measures & Vaccine Guidance
CDPH advises that mpox testing be considered for sexually active individuals with rash or lesions, regardless of vaccination status.
Vaccination is recommended for those at risk, including those who have not yet completed their doses or did not receive vaccine during earlier outbreaks.
Pharmacies and clinics in California offer the JYNNEOS vaccine, often the set of two doses.
Booster (third) doses are not recommended at this time in California.
Providers are urged to consider mpox in routine sexual health exams, especially when STI testing is done.
5. Risk Outlook & Public Health Response
The public health risk is moderate but rising.
With more mobility, social events, and gaps in vaccination, California must stay vigilant.
Wastewater surveillance, contact tracing, and targeted vaccination efforts are key tools.
State and local health departments continue outreach to vulnerable populations.
Data Table: California Mpox Case Trends & Key Metrics
| Metric | Value / Trend (2022-2025) | Notes / Interpretation |
|---|---|---|
| Total cases (May 2022–Aug 2024) | 6,469 cases | From CDPH/CDC studies |
| Prolonged infections | 82 cases (≈1.3%) | Lasting >28 days |
| Vaccinated among prolonged | Very few had 2 doses | Suggests vaccine helps reduce chronic cases |
| Weekly cases (Aug 2025 average) | ~13 new cases/week | Increase from previous months |
| New strain case detected | 1 confirmed clade I case in 2024 | Imported travel-linked |
Symptoms, Transmission, & Clinical Facts
- Symptoms: Fever, swollen lymph nodes, headache, muscle pains, rash/lesions (especially on genital, face, hands)
- Incubation: 3 to 17 days usually
- Transmission: Direct contact with lesions, body fluids, contaminated objects; less commonly via prolonged respiratory droplets
- Even vaccinated or previously infected individuals can get milder disease in 2025 settings.
FAQs on California Mpox Cases
Q1: Are mpox cases rising in California in 2025?
Yes. Cases averaged ~13 per week in August 2025, a clear rise from earlier months.
Q2: What’s the significance of a clade I case?
It’s the first confirmed in the U.S., a strain historically more severe. But no major spread has been documented from that case.
Q3: Who is most affected?
Most cases are among men who have sex with men, HIV positive individuals, and those with lower vaccination coverage.
Q4: Does vaccination stop mpox entirely?
Vaccination reduces severity, spread, and chronic cases, but it does not offer 100% immunity.
Q5: What steps should individuals in California take?
Get vaccinated if eligible, use safe sexual practices, watch for lesions, seek medical care, and avoid close contact if symptoms appear.
Trusted Source
For official updates and detailed mpox data in California, see the California Department of Public Health surveillance pages.
Also, peer-reviewed meta review on mpox epidemiology (2022–2025) adds global insight:
You should also read about lyme disease
Conclusion
California is seeing renewed mpox activity in 2025.
The rise in clade II cases, the detection of clade I, and prolonged infections highlight evolving risk.
Public health measures—vaccination, testing, awareness—are more important than ever.
Being informed and proactive is the best defense.
Disclaimer
This article is for educational and informational purposes only.
It is not medical advice.
If you or someone you know shows symptoms, please consult licensed healthcare professionals.