Since 2022, over 102,000 cases of mpox clade IIb have been reported worldwide, primarily affecting men who have sex with men. Key risk factors include the use of HIV pre-exposure prophylaxis (PrEP) and HIV infection. In Denmark, the smallpox vaccine (Imvanex) has been available to at-risk individuals since 2022. However, cases of reinfection with mpox have raised concerns about immunity, asymptomatic transmission. Between August and October 2023, we screened 123 PrEP users for mpox at an outpatient clinic at Copenhagen University Hospital Hvidovre, Denmark. Mpox PCR testing was conducted using rectal swabs. Among the participants, 97% had received at least one dose of the mpox vaccine. No mpox cases were detected. These findings suggest that, in a highly vaccinated high-risk population during a period of very low mpox prevalence in Denmark, asymptomatic mpox circulation is unlikely. The results support the current strategy of focusing mpox testing on symptomatic individuals and contact tracing during low-prevalence periods with high vaccination coverage.

The authors have declared no competing interest.

This study did not receive any funding

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Ethics committee/IRB of Region Hovedstaden; Hvidovre/Amager Hospital gave ethical approval for this work

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