Changes in Dengue Epidemiology in China Before, During, and After COVID‐19 2015–2024: A Retrospective National Surveillance and Spatiotemporal Study
Yu Chen, Meng Shang, Shengping Dou, Xiaoxu Wang, Haoqiang Ji, Qiyong LiuABSTRACT
Background
Dengue remains a major mosquito‐borne disease in China. The COVID‐19 pandemic and associated non‐pharmaceutical interventions (NPIs) profoundly altered human mobility and public health responses, potentially reshaping dengue transmission dynamics. However, comprehensive nationwide evidence on their long‐term epidemiological impact is limited.
Objective
This study aimed to evaluate changes in dengue epidemiology in China before, during, and after the COVID‐19 pandemic, with a focus on temporal periodicity, importation and indigenous transmission, counterfactual deviations from pre‐pandemic trends, and spatial risk redistribution.
Methods
We conducted a nationwide retrospective spatiotemporal study using reported dengue cases in China from 2015 to 2024. Epidemiological characteristics were compared across pre‐pandemic, pandemic, and post‐pandemic phases. Morlet wavelet analysis was used to assess temporal periodicity. A SARIMA model fitted to pre‐pandemic data generated counterfactual forecasts for 2020–2024. Spatial patterns were evaluated using provincial incidence mapping, Global Moran's I , and Local Indicators of Spatial Association.
Results
A total of 87 182 dengue cases were reported, with major peaks in 2019 and 2024. Imported cases declined sharply during 2020–2022 and rebounded after 2023, whereas indigenous transmission became increasingly dominant. Annual periodicity weakened during the pandemic but re‐emerged after 2023. Observed incidence during 2020–2022 was frequently below counterfactual expectations, while substantial positive deviations appeared from mid‐2023 and intensified in 2024. Post‐pandemic dengue risk re‐emerged in South and Southwest China and expanded inland, with weaker provincial clustering.
Conclusions
COVID‐19 and related NPIs substantially reshaped dengue epidemiology in China, suppressing transmission during 2020–2022 but followed by a marked post‐pandemic resurgence, increasing indigenous transmission, disrupted but re‐emerging seasonality, and broader inland spread.