Institute of Healthy Geography, School of Geography and Tourism, Shaanxi Normal University, Xi'an, 710119, China.
Department of Cardiology, The Second Affiliated Hospital of Medical College, Xi'an Jiaotong University, Xi'an, 710004, China.
BMC Public Health. 2023 Sep 1;23(1):1685. doi: 10.1186/s12889-023-16646-z.
Currently, the influenza epidemic in China is at a high level and mixed with other respiratory diseases. Current studies focus on regional influenza and the impact of environmental pollutants on time series, and lack of overall studies on the national influenza epidemic and the nonlinear correlation between environmental pollutants and influenza. The unclear spatial and temporal evolution patterns of influenza as well as the unclear correlation effect between environmental pollutants and influenza epidemic have greatly hindered the prevention and treatment of influenza epidemic by relevant departments, resulting in unnecessary economic and human losses.
This study used Chinese influenza incidence data for 2007-2017 released by the China CDC and air pollutant site monitoring data. Seasonal as well as inter monthly differences in influenza incidence across 31 provinces of China have been clarified through time series. Space-Time Cube model (STC) was used to investigate the spatio-temporal evolution of influenza incidence in 315 Chinese cities during 2007-2017. Then, based on the spatial heterogeneity of influenza incidence in China, Generalized additive model (GAM) was used to identify the correlation effect of environmental pollutants (PM, PM, CO, SO, NO, O) and influenza incidence.
The influenza incidence in China had obvious seasonal changes, with frequent outbreaks in winter and spring. The influenza incidence decreased significantly after March, with only sporadic outbreaks occurring in some areas. In the past 11 years, the influenza epidemic had gradually worsened, and the clustering of influenza had gradually expanded, which had become a serious public health problem. The correlation between environmental pollutants and influenza incidence was nonlinear. Generally, PM, CO and NO were positively correlated at high concentrations, while PM and SO were negatively correlated. O was not strongly correlated with the influenza incidence.
The study found that the influenza epidemic in China was in a rapidly rising stage, and several regions had a multi-year outbreak trend and the hot spots continue to expand outward. The association between environmental pollutants and influenza incidence was nonlinear and spatially heterogeneous. Relevant departments should improve the monitoring of influenza epidemic, optimize the allocation of resources, reduce environmental pollution, and strengthen vaccination to effectively prevent the aggravation and spread of influenza epidemic in the high incidence season and areas.
目前中国正处于流感高发期，且与其他呼吸道疾病混合流行。现有研究多集中于区域性流感及环境污染物对时间序列的影响，缺乏对全国流感疫情的整体研究以及环境污染物与流感的非线性关联研究。流感时空演变规律不清晰，环境污染物与流感流行的关联效应不明确，极大地阻碍了相关部门对流感疫情的防控，造成不必要的经济和人员损失。
本研究使用中国疾病预防控制中心发布的 2007-2017 年中国流感发病率数据和空气污染物站点监测数据，通过时间序列方法明确了中国 31 个省份流感发病率的季节性和月际差异。采用时空立方模型（STC）对 2007-2017 年全国 315 个城市的流感发病率时空演变进行了研究。然后，基于中国流感发病率的空间异质性，采用广义加性模型（GAM）识别环境污染物（PM2.5、PM10、CO、SO2、NO2、O3）与流感发病率的关联效应。
中国流感发病率具有明显的季节性变化，冬春季高发。3 月以后流感发病率明显下降，仅在部分地区偶有散发。在过去 11 年中，流感疫情呈逐渐加重趋势，聚集性逐渐扩大，已成为严重的公共卫生问题。环境污染物与流感发病率的关联是非线性的。一般来说，在高浓度下，PM2.5、CO 和 NO2 呈正相关，而 PM10 和 SO2 呈负相关。O3 与流感发病率的相关性不强。
本研究发现，中国流感疫情处于快速上升阶段，部分地区呈多年暴发趋势且热点不断向外扩展。环境污染物与流感发病率的关联是非线性和空间异质的。相关部门应加强流感疫情监测，优化资源配置，降低环境污染，加强疫苗接种，在高发季节和地区有效防控流感疫情的加重和扩散。
