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Nowcasting and Forecasting Seasonal Influenza Epidemics - China, 2022-2023

journal contribution
posted on 2024-05-09, 02:14 authored by Zhanwei Du, Zengyang Shao, Xiao Zhang, Ruohan Chen, Tianmu Chen, Yuan Bai, Lin Wang, Eric LauEric Lau, Benjamin J Cowling
Background: Seasonal influenza resurged in China in February 2023, causing a large number of hospitalizations. While influenza epidemics occurred across China during the coronavirus disease 2019 (COVID-19) pandemic, the relaxation of COVID-19 containment measures in December 2022 may have contributed to the spread of acute respiratory infections in winter 2022/2023. Methods: Using a mathematical model incorporating influenza activity as measured by influenza-like illness (ILI) data for northern and southern regions of China, we reconstructed the seasonal influenza incidence from October 2015 to September 2019 before the COVID-19 pandemic. Using this trained model, we predicted influenza activities in northern and southern China from March to September 2023. Results: We estimated the effective reproduction number Re as 1.08 [95% confidence interval (CI): 0.51, 1.65] in northern China and 1.10 (95% CI 0.55, 1.67) in southern China at the start of the 2022-2023 influenza season. We estimated the infection attack rate of this influenza wave as 18.51 % (95% CI: 0.00%, 37.78%) in northern China and 28.30% (55% CI: 14.77%, 41.82%) in southern China. Conclusions: The 2023 spring wave of seasonal influenza in China spread until July 2023 and infected substantial number of people.

History

Journal

China CDC Weekly

Volume

5

Pagination

1100-1106

Location

Beijing, China

ISSN

2096-7071

eISSN

2096-7071

Language

English

Publication classification

C1 Refereed article in a scholarly journal

Issue

49

Publisher

Chinese Center for Disease Control and Prevention