Abstract: Objective To compare the epidemiological differences of dengue fever in Guangzhou before and after the COVID-19 epidemic, analyze challenges in its prevention and control, and propose future prevention and control strategies. Methods Data on dengue cases reported in Guangzhou from 2017 to 2023 were collected and divided into three groups based on time periods: the pre-COVID-19 group (2017-2019), the during-COVID-19 group (2020-2022), and the post-COVID-19 group (2023). The epidemiological characteristics of the three groups were described, and the time interval from case onset to reporting and changes in mosquito vector density at epidemic sites before and after the COVID-19 epidemic were calculated and compared. Results In the year following the COVID-19 epidemic, 1 801 dengue cases were reported in Guangzhou, which was higher than during the COVID-19 epidemic (21 cases reported annually) and before the COVID-19 epidemic (1 297 cases reported annually). The median onset-to-reporting time (M, IQR) for dengue fever cases in Guangzhou decreased significantly from 4 (4) days in 2017-2019 to 3 (3) days in 2023 (P<0.01). The average standard space index (SSI) for the first evaluation of mosquito vector density in the core area of dengue fever outbreak was 2.58 in 2017-2019, which decreased to 0.28 on the 7th day of intervention; In 2023, The SSI for the first evaluation of mosquito vector density in the core area of dengue fever was 3.54, dropping to 2.43 on the 7th day of intervention. Conclusions Following adjustments to COVID-19 prevention policies, the epidemic situation of dengue fever in Guangzhou returned to pre-COVID-19 levels after a three-year low-incidence period. Post-COVID-19, the surveillance sensitivity for dengue cases in Guangzhou was improved; but grassroots response capacity to dengue fever declined.

Key words: The COVID-19 Pandemic, Dengue fever, Epidemiological characteristics