Logistic模型在甲型H1N1流感大流行模拟中的应用

Application of Logistic model in simulating influenza A( H1N1) pandemic

目的 采用Logistic模型模拟甲型H1N1流感大流行过程. 方法 使用Logistic模型对长沙市甲型H1N1流感大流行疫情进行拟合,确定模型的参数;推导模型的3个关键点,对大流行疫情进行定量分期. 结果 长沙市甲型H1N1流感疫情可以分为“输入期”、“本地扩散期”、“大流行期”三个时期.“大流行期”的Logistic模型方程为：n=6878/1＋e-（0.1166t-8.3859）.模型模拟结果显示,“大流行期”分为三个阶段：①渐增期（第105～166 d）,在该时期,疫情发展缓慢,是采取防控措施的最佳时期;②快增期（第167～ 188 d）,此时期的防控难度较大,付出的防控成本可能收不到预期的效果;③缓增期（第189～244 d）,在该时期,免疫屏障已逐步建立,采取防控措施效果将不明显. 结论 Logistic模型能较好地模拟城市甲型H1N1流感大流行过程.

Objective To simulate the spreading process of influenza A （H1NI） pandemic with Logistic model. Methods Data about influenza A （H1N1） pandemic in Changsha were employed for simulating and confirming the parameters of the mod- al. 3 critical points of the model were deduced for dividing the pandemic into different stages. Results The influenza A （H1 N1 ） pandemic in Changsha could be divided into three phases, including ＂case - import phase＂, ＂local - case - spread phase＂ and ＂pandemic phase＂. Logistic model equation of ＂pandemic phase＂ was n=6878/1＋e-（0.1166t-8.3859） The predictive results of the model showed that the pandemic was expected to experience three phrases： （1） increasingly growing stage （105th- 166th d）, in which the epidemic developed slowly and could be intervened relatively easilyl （2） rapidly growing stage （167th- 188th d）, in which it was difficult to take preventive measures and might pot receive expected effectiveness at greater cast; （3） relaxedly growing stage （189th- 244tb d）, in which immunological barrier had been built up and the efficacy of the preventive measures was not significant. Conclusions Influenza A （H1N1） pandemic can be simulated perfectly by Logistic model.