Temporal and Spatial Evolution and Prevention and Control Management of the "5·21" COVID-19 in Guangzhou

The "5·21" epidemic in Guangzhou was the first local outbreak in China caused by the COVID-19 mutation (Delta). This study analyzed the statistical characteristics, diffusion network, and prevention and control management of the epidemic domestically and globally, using infected persons during the "5·21" epidemic in Guangzhou as an example. The research methods include statistical analysis, text analysis and social network analysis. The research conclusions showed: (1) that most infected people during the epidemic were older adults. The virus incubation period was short and spread quickly. Furthermore, nucleic acid detection and screening can accurately control the risk of virus transmission within a known range. The virus's travel path in Guangzhou helped clarify the transmission chain timeously and cut off the transmission route. (2) The infected persons in Guanzhou were distributed in fragments and distributed throughout the region, town streets, key areas, and designated prevention and control management areas. The infected persons were clustered in a few towns and streets in Guangzhou. The epidemic spread in Guangzhou is mainly due to interpersonal contact and has airborne spread characteristics. (3) The virus spread happened in "cluster" and "chain" formations. This network presents "small world" characteristics as a whole. In Guangzhou, nodes with high index values at the network node level have established extensive contact relations with other nodes and are on the key path of the epidemic contact diffusion network. They are the key objects of hierarchical and classified epidemic prevention and control management. (4) The "5·21" epidemic situation in Guangzhou shows the hierarchical and classified prevention and control management measures should include 10 aspects: access management, community control, home isolation, demand guarantee, domestic waste treatment, environment disinfection, health monitoring and services, nucleic acid detection, publicity and guidance, control lifting.