Spatiotemporal analysis on influenza in Hangzhou, Zhejiang, 2019–2020

  Objective  To analyze the temporal and spatial distribution of influenza epidemics in Hangzhou, and provide evidence for influenza prevention and control.

  Methods  The influenza incidence data in Hangzhou during 2019–2020 were collected from “China Disease Prevention and Control Information System”, and the influenza outbreak data in Hangzhou during this period were derived from the epidemic response reports of Centers for Disease Control and Prevention in Hangzhou. Software ArcGIS 10.2 was used for global/local spatial autocorrelation analysis, and software SaTScan was used for spatiotemporal epidemiological analysis.

  Results  A total of 264 410 influenza cases were reported in Hangzhou from January 1, 2019 to September 30, 2020, with an incidence rate of 269.98 per 10 000. The incidence peak was during December 2019 – January 2020 with cases accounting for 66.54% of the total. GSA Moran’s I value from the first quarter of 2019 to the first quarter of 2020 was positive and statistically significant (P<0.001). A total of 71 areas with high-high clustering were detected by local spatial association analysis, mainly located in the urban area and surrounding areas of Hangzhou. The spatiotemporal analysis showed that the class Ⅰ clustering areas were mainly located in the urban area and the surrounding areas of Hangzhou during December 15 2019 – January 25 2020, and the relative risk (RR) was 20.86, the log likelihood ratio (LLR) was 142 431.21 (P<0.001). The clustering areas detected by local spatial autocorrelation analysis and spatiotemporal analysis were similar to the actual outbreak distribution.

  Conclusion  Temporal and spatial clustering of influenza incidence existed in Hangzhou during 2019–2020. Influenza prevention and control in the main urban areas and surrounding areas should be strengthened from November to January of the following year.