A peer-educator driven approach for sampling populations at increased mpox risk in the Democratic Republic of the Congo: Implications for surveillance and response.

The epidemiological risk factors associated with mpox acquisition and severity in the Democratic Republic of the Congo (DRC) are changing. We assessed perceived mpox risk, and behavioral, clinical and sexual histories among key populations at risk of acquisition through sexual contact. Here, we describe a sampling strategy to enroll participants considered to be at increased risk for mpox infection - men who have sex with men (MSM) and sex workers (SW) - in three urban centers in the DRC. Through the combined approach of time-location sampling with peer educators and respondent-driven sampling, a mixed cohort of 2826 individuals including self-identified MSM (n = 850), SW (n = 815), both MSM and SW (n = 118) and non-MSM, non-SW individuals (n = 1043) were enrolled in Kinshasa, Kinshasa province, Kenge, Kwango province, and Goma, North Kivu province, from March-August 2024. Of these, over 90% were reached through peer educators. The odds of sampling SW individuals were higher at bars/clubs than traditional health facilities. Conversely, the odds of enrolling MSM were highest at selected health facilities. Modifications to the sampling approach were introduced in Kenge and Goma, but these did not affect the enrollment of MSM or SW participants. Ultimately, the selection of, and collaboration with, well-integrated peer educators was the most important facet of this sampling strategy. As the definitions of at-risk populations continue to change for mpox, we demonstrate a functional approach to quickly surveying otherwise hard-to-reach groups for both public health surveillance activities and response.