Objective To analyze the seasonal epidemiological characteristics of influenza in Guangdong province from 2018 to 2024 and provide scientific evidence for influenza epidemic assessment and response in the future.

Methods The incidence data of influenza reported in Guangdong from 2018 to 2024 were collected, and the seasonal characteristics of influenza was analyzed by using seasonal index, wavelet analysis and moving epidemic method (MEM).

Results The average annual incidence rate of influenza in Guangdong during this period was 501.02/100 000. The incidence of influenza was high during December - January and during March - June, and the seasonal indexes were all higher than 100%. The average wavelet power peaked every other 0.40-years, and the half year epidemic duration was significant in most years (P<0.05). MEM analysis showed that influenza epidemics occurred in five surveillance periods. The epidemic usually lasted for less than 10 weeks, the incidence peak was mainly observed in winter (December - January). During 2020-2024, the incidence seasonality was affected, no epidemic was detected during 2020-2021, the incidence peak occurred in summer (June) during 2021-2022. The 2022-2023 winter influenza season was later compared with previous years, peaking in April with the highest recorded incidence rate (138.47/100 000). The 2023-2024 winter influenza season started earlier with a relatively high peak intensity (127.70/100 000).

Conclusions The annual influenza epidemic usually lasted for half year in Guangdong from 2018-2024, with two incidence peaks mostly occurred in winter and during spring - summer. The seasonality was affected during 2020-2024 without epidemic season and with changed epidemic season, rapid incidence rebound following the decline after incidence peak, and prolonged epidemic durations. It is necessary to strengthen influenza surveillance in the post- pandemic period and identify key seasonal epidemic periods to optimize vaccination strategies and public health intervention.