长沙市某校甲型H1N1流感暴发过程及其防控策略效果的Logistic模型模拟

目的采用Logistic模型模拟甲型H1N1流感的暴发过程,并评估暴发疫情防控措施的效果。方法使用Logistic模型对长沙市某校甲型H1N1流感暴发疫情进行拟合,确定模型的参数,并进行拟合优度检验,探讨模型的适用性;推导模型的3个关键点,对暴发疫情进行定量分期;利用拟合后获得的模型进行暴发疫情预测,将预测结果与实际防控结果进行比较,评价防控效果。结果无干预情况下,甲型H1N1流感暴发疫情病例数与Logistic模型仿真的病例数差异无统计学意义（χ2=3.94,P=0.786）。模型预测结果显示,暴发疫情分为3个阶段：渐增期（第1~14天）,在该时期,疫情发展缓慢,是采取防控措施的最佳时期;快增期（第14~20天）,此时期的防控难得较大,付出的防控成本可能收不到预期的效果;缓增期（第20天以后）,在该时期,免疫屏障逐步建立,采取防控措施无较大意义。Malthusian模型模拟结果也显示,疾控部门越早干预,取得的防控效果越好。实际联防联控的综合防控措施能减少92.62%病例的发生,干预取得了很好的效果。结论甲型H1N1流感暴发疫情的发展迅速,在疫情渐增期采取综合防控措施能取得较好效果。

Simulation of influenza A(H1N1) outbreak and the effect of interventions with Logistic model in a school in Changsha City

Objective To simulate influenza A（ H1N1） outbreaks and the effect of intervention with the Logistic model. Methods A school influenza A（ H1N1） outbreak of Changsha was employed for simulation. Parameters of the model were determined,and Chi square test was conducted to assess the fit of the model. The outbreak was divided into different stages by using 3 deduced strategic points of the model. At last,the outbreak were predicted,and the predict results were compared with reported data for assessing effect of measures. Results Without interventions,there was no significant difference between cases from influenza A（ H1N1） outbreaks and cases from Logistic model（ χ2= 3. 94,P = 0. 786）. The predictive results of model showed that the outbreak was expected to experience three phrases： increasingly growing stage（ 1-14 days） in which the epidemic developed slowly and could be intervened easily; rapidly growing stage（ 14-20 days） in which it was difficult to take preventive measures and might not receive expected effect although it might cost a lot; and slowly growing stage（ after 20 days） in which adaptive immunity was built up,and there was no significant difference to take measures. The simulated result of Malthusian model revealed that the desivable effects are coherent with early intervention. The incidence of cases could be reduced by 92. 62% via joint comprehensive prevention and control measures,suggesting a good effect by interventions. Conclusions Influenza A（ H1N1） transmits quickly in the school outbreak. The effect can be achieved when the interventions are taken in increasingly growing stage of the outbreak.