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. 2024 Jan 18;73(2):44-48.
doi: 10.15585/mmwr.mm7302a4.

Mpox Outbreak - Los Angeles County, California, May 4-August 17, 2023

Colleen M Leonard, Kathleen Poortinga, Erin Nguyen, Abraar Karan, Sonali Kulkarni, Rebecca Cohen, Jacob M Garrigues, Amy N Marutani, Nicole M Green, Andrea A Kim, Kwa Sey, Mario J Pérez

Mpox Outbreak - Los Angeles County, California, May 4-August 17, 2023

Colleen M Leonard et al. MMWR Morb Mortal Wkly Rep. .

Abstract

Since May 2022, approximately 2,500 mpox cases have been reported in Los Angeles County (LAC), California. Beginning in May 2023, the LAC Department of Public Health observed a consistent increase in mpox cases after a prolonged period of low incidence. A total of 56 cases were identified during May 4-August 17, 2023. A minority of mpox patients were fully vaccinated (29%). One patient was hospitalized; no deaths were reported. Two cases of reinfection occurred, both of which were associated with mild illness. The increasing number of cases during this period was significant, as few other health departments in the United States reported an increase in mpox cases during the same period. The outbreak spread similarly to the 2022 U.S. mpox outbreak, mainly through sexual contact among gay, bisexual, and other men who have sex with men. Vaccination against mpox became available in June 2022 and has been shown to be effective at preventing mpox disease. This outbreak was substantially smaller than the 2022 mpox outbreak in LAC (2,280 cases); possible explanations for the lower case count include increased immunity provided from vaccination against mpox and population immunity from previous infections. Nonetheless, mpox continues to spread within LAC, and preventive measures, such as receipt of JYNNEOS vaccination, are recommended for persons at risk of Monkeypox virus exposure.

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Conflict of interest statement

All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. Abraar Karan received funding from the National Institutes of Health. Nicole M. Green reports serving as president of the Southern California Branch of the American Society for Microbiology. Mario J. Pérez reports institutional support from the Ryan White Program Parts A, B, MAI, and EHE and leadership in the National Coalition of STD Directors. No other potential conflicts of interest were disclosed.

Figures

FIGURE
FIGURE
Laboratory-confirmed mpox cases, by episode date (N = 56) — Los Angeles County, California, May 4–August 17, 2023 Abbreviation: LACDPH = Los Angeles County Department of Public Health. * Episode date is calculated from the symptom onset date or, if the symptom onset date is unknown, from specimen collection date.
See this image and copyright information in PMC

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