Shandong Provincial Key Laboratory of Infectious Disease Control and Prevention, Shandong Center for Disease Control and Prevention, Jinan, China.
School of Public Health, Shandong First Medical University and Shandong Academy of Medical Sciences, Tai'an, China.
Influenza Other Respir Viruses. 2022 May;16(3):594-603. doi: 10.1111/irv.12959. Epub 2022 Jan 11.
Understanding the influenza-like illness (ILI) incidence, circulation pattern of virus strains and spatiotemporal pattern of influenza transmission are important for designing control interventions. Based on the 10 years' surveillance data, we aimed to provide a baseline characterization and the epidemiology and dynamics of influenza virus in Shandong.
We extracted surveillance and laboratory testing data. We estimated the ILI incidence and analyzed the predominant virus. A wavelet power analysis was used to illustrate the periodicity. In addition, we applied a linear regression model to characterize the correlation of influenza seasonality with longitude.
The average ILI incidence was estimated to be 3744.79 per 1 million (95% confidence interval [CI]: 2558.09-4931.45) during 2009-2018. Influenza A/H1N1 and A/H3N2 strains predominated in the most influenza seasons in Shandong. The annual amplitude of influenza epidemics decreased with longitude (P < 0.05). In contrast, the epidemic peak of influenza emerged earlier in the western region and increased with longitude in influenza A (P < 0.05). The annual peak of the influenza B epidemic lagged a median of 4.2 weeks compared with that of influenza A.
The development or modification of seasonal influenza vaccination strategies requires the recognition that the incidence is higher in preschool- and school-aged children. Although seasonal influenza circulates annually in Shandong, the predominant virus strain circulation pattern is extremely unpredictable and strengthening surveillance for the predominant virus strain is necessary. Lower longitude inland regions need to take nonpharmaceutical or pharmaceutical interventions in advance during influenza high-occurrence seasons.
了解流感样疾病（ILI）的发病率、病毒株的循环模式和流感传播的时空模式，对于设计控制干预措施非常重要。基于 10 年的监测数据，我们旨在为山东流感病毒的基本特征、流行病学和动力学提供基线描述。
我们提取了监测和实验室检测数据。我们估计了 ILI 的发病率并分析了主要病毒。应用小波功率分析来说明周期性。此外，我们应用线性回归模型来描述流感季节性与经度的相关性。
2009-2018 年期间，平均 ILI 发病率估计为每 100 万人 3744.79 例（95%置信区间[CI]：2558.09-4931.45）。在山东，流感 A/H1N1 和 A/H3N2 株在大多数流感季节中占主导地位。流感流行的年振幅随经度而减小（P<0.05）。相反，流感 A 的西部地区的流行高峰出现较早，并随经度增加而增加（P<0.05）。与流感 A 相比，流感 B 的年度流行高峰滞后中位数 4.2 周。
季节性流感疫苗接种策略的制定或修改需要认识到学龄前和学龄儿童的发病率更高。尽管流感在山东每年都会流行，但主要病毒株的循环模式极不可预测，因此有必要加强对主要病毒株的监测。低经度内陆地区在流感高发季节需要提前采取非药物或药物干预措施。
