Huang Weijuan, Li Xiyan, Tan Minju, Cheng Yanhui, Chen Tao, Wei Hejiang, Zeng Xiaoxu, Xie Yiran, Liu Jia, Xiao Ning, Yang Lei, Wang Dayan
National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention; WHO Collaborating Centre for Reference and Research on Influenza; Key Laboratory for Medical Virology, National Health Commission, Beijing, China.
China CDC Wkly. 2021 Oct 29;3(44):918-922. doi: 10.46234/ccdcw2021.224.
During the coronavirus disease 2019 (COVID-19) pandemic, the circulation of seasonal influenza virus declined globally and remained below previous seasonal levels. We analyzed the results of the epidemiology, antigenic, and genetic characteristics, and antiviral susceptibilities of seasonal influenza viruses isolated from the mainland of China during October 5, 2020 through September 5, 2021, to better assess the risk of influenza during subsequent influenza season in 20212022.
Positive rates of influenza virus detection during this period were based on real-time polymerase chain reaction (PCR) detection by the Chinese National Influenza Surveillance Network laboratories, and isolated viruses from influenza positive samples were submitted to the Chinese National Influenza Center. Antigenic analyses for influenza viruses were conducted using the hemagglutination inhibition assay. Next-generation sequencing was used for genetic analyses. Viruses were tested for resistance to antiviral medications using a phenotypic assay and next-generation sequencing.
In southern China, the influenza positivity rate was elevated especially after March 2021 and was higher than the same period the previous year with the COVID-19 pandemic. In northern China, influenza positive rate peaked at Week 18 in 2021 and has declined since then. Nearly all isolated viruses were B/Victoria lineage viruses during the study period, and 37.3% of these viruses are antigenically similar to the reference viruses representing the vaccine components for the 2020-2021 and 2021-2022 Northern Hemisphere influenza season. All seasonal influenza viruses were susceptible to neuraminidase inhibitors and endonuclease inhibitors.
Influenza activity has gradually increased in the mainland of China in 2021, although the intensity of activity is still lower than before the COVID-19 pandemic. The diversity of circulating influenza types/subtypes decreased, with the vast majority being B/Victoria lineage viruses. The surveillance data from this study suggest that we should strengthen influenza surveillance during the upcoming traditional influenza season. It also provided evidence for vaccine recommendations and prevention and control of influenza and clinical use of antiviral drugs.
在2019年冠状病毒病（COVID-19）大流行期间，季节性流感病毒在全球的传播有所下降，且仍低于以往季节性水平。我们分析了2020年10月5日至2021年9月5日期间从中国内地分离出的季节性流感病毒的流行病学、抗原性、基因特征及抗病毒敏感性结果，以便更好地评估2021-2022年后续流感季节的流感风险。
在此期间流感病毒检测的阳性率基于中国国家流感监测网络实验室的实时聚合酶链反应（PCR）检测，从流感阳性样本中分离出的病毒被提交至中国国家流感中心。采用血凝抑制试验对流感病毒进行抗原分析。使用二代测序进行基因分析。采用表型试验和二代测序检测病毒对抗病毒药物的耐药性。
在中国南方，流感阳性率有所升高，尤其是在2021年3月之后，且高于COVID-19大流行期间的上一年同期。在中国北方，流感阳性率在2021年第18周达到峰值，此后有所下降。在研究期间，几乎所有分离出的病毒均为B/维多利亚系病毒，其中37.3%的病毒在抗原性上与代表2020-2021年及2021-2022年北半球流感季节疫苗成分的参考病毒相似。所有季节性流感病毒均对神经氨酸酶抑制剂和核酸内切酶抑制剂敏感。
2021年中国内地的流感活动已逐渐增加，尽管活动强度仍低于COVID-19大流行之前。流行的流感型别/亚型的多样性有所下降，绝大多数为B/维多利亚系病毒。本研究的监测数据表明，我们应在即将到来的传统流感季节加强流感监测。它还为流感疫苗推荐、预防控制以及抗病毒药物的临床使用提供了依据。
