Understanding the drivers of continued mpox transmission in the United States: a modeling study

Abstract

Abstract The 2022 mpox epidemic in the United States (U.S.) peaked in the summer of 2022, but over a year later, new cases continue to emerge. To understand why mpox continues to spread, albeit at low levels, we explored three mechanisms: (1) underdetection of cases, (2) waning immune protection from vaccination, and (3) waning immune protection from prior infection. We refined a multilayer epidemic network model to simulate these mechanisms and fit this model to the 2022 mpox outbreaks in Chicago, New York City, and San Francisco. Analyses across mechanisms suggest that underdetection was the most likely driver of prolonged transmission. Furthermore, the duration of simulated outbreaks was most sensitive to changes in the proportion of undetected cases. Our findings underscore the need for enhanced surveillance to capture the true scope of mpox transmission in the U.S., reduce the possibility of future resurgence, and enable effective outreach to key affected populations.