流感发病对短期天气变化强度的响应及风险预警研究

The response of influenza-like illnesses to short-term weather variability intensity and risk early warning

研究短期天气变化强度对湖北省流感发病的定量影响,对开展发病风险预警和制定防御对策具有重要意义。本文利用2009—2020年湖北省流感发病数据和气象站观测数据,通过建立一项衡量短期内相邻两周最低气温累积变化的短期天气变化强度(Short-term Weather Variability Intensity,SWVI)指数,基于分布滞后非线性模型(Distributed Lag Nonlinear Model,DLNM)定量评估SWVI指数与流感发病风险的关系,探讨流感发病风险预警等级划分方法。结果表明:湖北省流感样病例(Influenza-Like Illnesses,ILI)发病人数年内变化呈双峰型,峰值位于秋冬季,次高峰位于前夏;SWVI指数也呈双峰型,但峰值出现时间较ILI发病人数早。11月至次年3月,SWVI指数对ILI发病率的变化有较强的指示意义,该时段内当SWVI指数达到8.0℃时,同期至未来1周ILI发病的累积相对风险(Relative Risk,RR)达1.16(95%置信区间为:1.087~1.250);此外,SWVI还对滞后4—9周的ILI发病风险产生间接影响,相比即刻效应影响程度小,但持续时间长。利用百分位法及SWVI指数与ILI发病风险的关系模型,建立一套基于SWVI指数的流感发病风险预警方法,当SWVI大于等于8.0℃时,其对流感发病影响达高风险。

Exploring the quantitative impact of short-term weather variability intensity(SWVI)on influenza incidence in Hubei Prov⁃ince is of significant importance for conducting early risk warning and formulating prevention policies.Based on the influenza inci⁃dence data and meteorological station observation,an index of SWVI has been built,which can measure the cumulative changes over a short-term in minimum temperature between two consecutive weeks.Based on the Distributed Lag Nonlinear Model(DLNM),the rela⁃tion between SWVI index and influenza incidence risk was evaluated and a set of method for level classification of influenza incidence risk was developed.The results show that the intra-annual variation of number of Influenza-Like Illnesses(ILI)exhibited bimodal struc⁃ture,with the first peak occurring in autumn and winter,and the second peak appearing in early summer months.The SWVI index also exhibited a bimodal distribution,but the peak occurring earlier than the peak of ILI.From November to March of the following year,SWVI index had a strong indicative significance for the change of ILI morbidity.In this period,when SWVI reaches 8.0℃,the cumula⁃tive relative risk(RR)of ILI incidence at the same period and the next week was 1.16(95%confidence interval:1.087-1.250).In addi⁃tion,SWVI index also had an indirect effect on the risk of ILI with a lag of 4-9 weeks,which was less affected than the immediate ef⁃fect,but lasted longer.Using the percentile method and the relationship model between the SWVI index and the ILI incidence risk,a set of influenza risk early warning method was established.When the SWVI index was greater than or equal to 8.0℃,the influenza inci⁃dence reached high risk level.