Top 5 Takeaways

  1. Rise in Mpox Cases: Los Angeles County saw an increase in mpox cases from May to August 2023, with 56 cases reported, marking a higher rate than previous months and in comparison to other U.S. regions.
  2. Vaccination Gaps: A significant number of mpox patients were not fully vaccinated, with only 29% having received full vaccination, highlighting a need for increased vaccination efforts.
  3. Demographic Profile: The outbreak primarily affected males who identify as gay or bisexual. The median age was 35, with notable racial disparities in vaccination rates among different ethnic groups.
  4. Mild Reinfections Reported: Two mild cases of reinfection occurred among unvaccinated individuals who had a previous mpox diagnosis in 2022.
  5. Public Health Response: Efforts included vaccination drives, particularly before Pride events, and ongoing surveillance and educational outreach to control the spread of mpox.

Original Article Author and Citation

Corresponding Author

Colleen M. Leonard, MPH,

Suggested Citation

Leonard CM, Poortinga K, Nguyen E, et al. Mpox Outbreak — Los Angeles County, California, May 4–August 17, 2023. MMWR Morb Mortal Wkly Rep 2024;73:44–48. DOI:


This report details a mpox outbreak in Los Angeles County, California, from May 4 to August 17, 2023. A total of 56 cases were identified, with most patients not fully vaccinated against mpox. The outbreak mainly affected gay, bisexual, and other men who have sex with men, with a median patient age of 35 years. Racial disparities in vaccination rates were evident, particularly among Black and Hispanic communities.


The study involved interviewing Los Angeles County residents diagnosed with mpox to collect demographic, epidemiologic, and clinical information. The investigation also included genomic analyses of outbreak specimens for phylogenetic analysis.


The report discusses the continued spread of mpox within the county, with a focus on the importance of vaccination, particularly for high-risk groups. It compares the 2023 outbreak to previous outbreaks in terms of severity, demographic affected, and the effectiveness of public health responses like vaccination campaigns.


The mpox outbreak in Los Angeles County highlights the need for increased vaccination efforts, especially among high-risk groups, including young, Black or African American, and Hispanic or Latino persons, and persons living with HIV. The report emphasizes the importance of public health strategies in controlling the spread of mpox.

This has been your booster shot of MMWR Info! Please check back for more MMWR, Public Health, and Programming Tutorial content daily.

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes:

<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>