Abstract: Objective To investigate the incidence trend and spatial clustering characteristics of scarlet fever in China from 2016 to 2020 to provide evidence for development of regional disease prevention and control strategies. Methods The incidence data of scarlet fever in 31 provinces and municipalities in mainland China from 2016 to 2020 were obtained from the Chinese Health Statistics Yearbook and the Public Health Science Data Center led by the Chinese Center for Disease Control and Prevention. The three-dimensional spatial trend map of scarlet fever incidence in China was drawn using ArcGIS to determine the regional trend of scarlet fever incidence. GeoDa spatial autocorrelation analysis was used to explore the spatial aggregation of scarlet fever in China in recent years. Results From 2016 to 2020, a total of 310 816 cases of scarlet fever were reported in 31 provinces, municipalities directly under the central government and autonomous regions, with an average annual incidence of 4.48/100 000. The reported incidence decreased from 4.32/100 000 in 2016 to 1.18/100 000 in 2020 (Z=103.47, P<0.001). The incidence of scarlet fever in China showed an obvious regional clustering from 2016 to 2019 (Moran's I>0, P<0.05), but was randomly distributed in 2020 (Moran's I>0, P=0.16). The incidence of scarlet fever showed a U-shaped distribution in eastern and western regions of China, and increased gradually from the southern to northern regions. Inner Mongolia Autonomous Region and Hebei and Gansu provinces had the High-high (H-H) clusters of scarlet fever in China. Conclusion Scarlet fever still has a high incidence in China with an obvious spatial clustering. For the northern regions of China with H-H clusters of scarlet fever, the allocation of health resources and public health education dynamics should be strengthened, and local scarlet fever prevention and control policies should be made to contain the hotspots of scarlet fever.

Key words: scarlet fever; epidemic trend; spatial epidemiology; autocorrelation analysis