Chikungunya waves in 2025 signal risk of endemicity in China.

Chikungunya virus (CHIKV) transmission in Guangdong, southern China, intensified markedly in 2025, with successive outbreak waves in Foshan and Jiangmen followed by wider dissemination across all 21 prefectures during a peak domestic travel period. By late 2025, more than 25,000 cases had been reported, suggesting a departure from the historically import-driven and geographically limited outbreaks previously observed in China. These observations raise the possibility of an early transition towards more sustained transmission, although repeated introductions followed by local amplification remain an alternative explanation. Key contributing factors include mobility-associated amplification, climate variability, flood-related expansion of mosquito breeding habitats, favourable urban ecology, and incomplete interruption of transmission during cooler months. Although winter temperatures are suboptimal for sustained transmission, vector persistence and possible vertical viral transmission may permit low-level circulation between epidemic waves. In this context, distinguishing repeated importation from local persistence becomes critical. Preventing endemic establishment will require sustained inter-epidemic surveillance, anticipatory vector control, and clearer policy pathways for deployable vaccination strategies.