Objective: To evaluate the performance of the influenza surveillance network and compare the epidemic intensity of influenza during 2014-2020 in Shanghai. Methods: Based on the weekly reports of influenza-like illness (ILI) and laboratory-confirmed influenza cases from January 1, 2014 to December 31, 2020. This study first evaluated the data reporting and specimen collection of ILI cases for each sentinel hospital, and then calculated the percentage of ILI (ILI%), the proportion of specimens tested positive for influenza, and the incidence of influenza among all ILI outpatient and emergency visits to measure the epidemic intensity of influenza. Finally, seasonal autoregressive integrated moving average (ARIMA) model was applied to quantify the changes in epidemic intensity of influenza in 2020. Results: The proportion of influenza surveillance sentinel hospitals with a score of less than 5 in the evaluation of ILI data reporting and samples collection were 9.68% and 21.05% in 2020 in Shanghai, respectively. ILI% was estimated to be 1.51% (95%CI: 1.50%-1.51%) and 2.31% (95%CI: 2.30%-2.32%), respectively for 2014-2019 and 2020; the proportion of specimens tested positive was 24.27% (95%CI: 24.02%- 24.51%) and 7.15% (95%CI: 6.78%-7.54%), respectively; and the incidence of influenza was 3.66‰ (95%CI: 3.62‰-3.70‰) and 1.65‰ (95%CI: 1.57‰-1.74‰), respectively. ARIMA model showed that ILI% was increased by 45.25% in 2020 in Shanghai, and the proportion of specimens tested positive and the incidence of influenza were reduced by 78.45% and 51.80%, respectively. Conclusions: In 2020, the performance of influenza surveillance system has changed, ILI% has increased, the proportion of specimens tested positive and the incidence of influenza has decreased in Shanghai. The change in the quality of influenza surveillance is also a potential factor affecting the epidemic intensity of influenza. In the future, the quality control of influenza surveillance network still needs to be further strengthened.
目的： 评估上海市2014-2020年流感监测网络的运行情况以及流感发病强度的变化。 方法： 基于上海市2014年1月1日至2020年12月31日的流感监测数据，对哨点医院流感样病例（ILI）缺报漏报和ILI标本采集情况进行评价，计算ILI就诊百分比（ILI%）、流感病毒检出阳性率和流感发病率，利用季节性自回归移动平均模型构建“反事实”情况下2020年流感发病强度的基线，以定量估计上海市2020年流感发病强度的相对变化。 结果： 2020年上海市ILI缺报漏报情况评价得分和ILI标本采集情况评价得分<5分的医院占比分别为9.68%和21.05%。上海市2014-2019年和2020年的ILI%分别为1.51%（95%CI：1.50%~1.51%）和2.31%（95%CI：2.30%~2.32%），流感病毒检出阳性率分别为24.27%（95%CI：24.02%~24.51%）和7.15%（95%CI：6.78%~7.54%），流感发病率分别为3.66‰（95%CI：3.62‰~3.70‰）和1.65‰（95%CI：1.57‰~1.74‰）。上海市2020年的ILI%升高了45.25%，流感病毒检出阳性率和流感发病率分别降低了78.45%和51.80%。 结论： 2020年上海市流感监测网络的运行情况发生改变，ILI%有所升高，流感病毒检出阳性率和流感发病率均有所降低，流感监测质量的改变是一个潜在的影响因素，未来仍需进一步加强流感监测的质量控制。.