Two Peaks of Seasonal Influenza Epidemics — China, 2023

作者：Yiran Xie, Shuxia Lin, Xiaoxu Zeng, Jing Tang, Yanhui Cheng, Weijuan Huang, Jiandong Li, Dayan Wang · 发表于：China CDC Weekly · 年份：2024 · DOI：10.46234/ccdcw2024.069 · 被引用次数：20 · 研究领域：Influenza Virus Research Studies、Respiratory viral infections research、Data-Driven Disease Surveillance

Introduction: Influenza is a communicable respiratory disease that causes annual epidemics and occasional unpredictable pandemics. This study examines the occurrence of two unexpected influenza peaks within the year 2023. Methods: Influenza-like illness (ILI) data were reported, and specimens of ILI were collected by designated surveillance hospitals. Positive cases were confirmed using real-time reverse transcription polymerase chain reaction (rRT-PCR) testing conducted at national surveillance network laboratories. The data were then submitted to the Chinese Influenza Surveillance Information System. Results: From December 2022 to January 2023, influenza activity was minimal until a spring epidemic began in February, peaking in late March. The outbreak spread from the north to the south, with A(H1N1)pdm09 being the predominant strain and A(H3N2) also circulating concurrently. The positivity rate in northern and southern provincial-level administrative divisions (PLADs) reached 60.0% (week 10) and 60.2% (week 13), respectively, before dropping to below 5% from May to August. Subsequently, rates surged starting in week 41 in the south and week 44 in the north, peaking at 54.4% (week 50) and 44.0% (week 49), respectively, and remained high until the end of 2023. A(H3N2) became the prevailing strain, with a notable increase in B/Victoria lineage viruses from December, resulting in two peaks during the 2023 influenza season. Conclusions: The pattern of the influenza epidemic shi...