Mpox in the Republic of Korea from 2022 to June 2026: Epidemiological Trends and the First Clade Ib Case.

OBJECTIVES: Amid continuous global and domestic mpox transmission, the Republic of Korea (ROK) identified its first Clade Ib case in June 2026. This study examines cumulative incidence trends and epidemiological and virological characteristics from the initial 2022 outbreak through June 2026. METHODS: Demographic and geographical profiles, presumptive infection routes, and underlying conditions were analyzed using case notifications and epidemiological reports from the Korea Disease Control and Prevention Agency. For the recently confirmed Clade Ib case, whole-genome sequencing of viral DNA was performed to assess major genetic mutations and phylogenetic relationships with overseas sequences. RESULTS: From 2022 to June 2026, 205 confirmed mpox cases were reported in the ROK (2022: 4; 2023: 151; 2024: 17; 2025: 27; 2026: 6). Most patients were male (98.5%) and in their 20s (31.2%) or 30s (50.2%). The capital metropolitan area accounted for more than 80% of the reported cases. Of these, 189 were domestic infections and 16 were imported. Sexual contact was the primary mode of transmission, accounting for 84.9% (n=174) of the cases. Before June 2026, all identified patients were infected with Clade IIb. The newly identified Clade Ib virus shared 99.99% sequence similarity with strains from Europe, particularly Germany and Ireland, and harbored the characteristic C3L gene deletion. CONCLUSIONS: Following the large-scale epidemic in 2023, domestic mpox cases have occurred sporadically. The emergence of Clade Ib underscores the need for a sustained surveillance system. A transition toward a sustainable, prevention-oriented management framework is essential, complemented by vaccination of high-risk populations, promotion of personal hygiene measures, and clinician training to ensure timely recognition and treatment.