The Study Of The Optimal Intervention Timing And The Optimal Intervention Method Of Flu Outbreak In School

Objective: To analysis epidemic characteristics and intervention methods of school flu outbreak and to discuss the optimal intervention timing and the optimal intervention method, which can provide theoretical basis for prevention and control of influenza outbreak in school.Methods: The database of flu outbreak in school in 2004-2014 was established with articles published in CNKI, VIP and CHINAINFO. The epidemiological characteristics of the outbreaks and the intervention methods were analyzed. Multiple factors analysis was used to discuss the optimal intervention timing of flu outbreak in school. The transmission dynamics model was used to analysis the optimal intervention method with the data of a flu outbreak in one of a primary school in Chongqing collected from the "public health emergency reporting system" of Chongqing center for disease control and prevention. Researched intervention methods were three kinds of nine, which were measures for cases(treatment + isolation), measures for exposed(health education + morning check +drug prophylaxis+ school closure +vaccine) and measures for environment(disinfection +ventilation).Without the consideration of cost, the disease duration, the number of cases, the attact rate and the percentage of attact rate reduction were evaluation indexes. The cost-effectiveness ratio was evaluation indexes when take cost into consideration.Results:1.107 articles was collected with 109 flu outbreaks in school.Epidemiological characteristics of flu outbreak in school, 2004-2014:(1)Virus type: The H1N1 was the priority virus type(47.17%), followed by type B(30.19%)and H3N2(22.64%).(2) Unit: Most of school flu outbreaks occurred in primary school(47.06%), followed by middle school(35.29%) and only a few of flu outbreak occured in university/technical school(10.78%).(3)North-south distribution: 82(75.93%) school flu outbreaks were in the south of China and 26(24.07%) were in the north.(4)Rural and urban distribution: 57(54.81%) school flu outbreaks were in city when 47(45.19%)occurred in the countryside.(5)The duration: The shortest duration was 4 days and the longest duration was 46 days. The duration of 81(74.31%) outbreaks was longer than 10 days, while the duration of 18(16.51) outbreaks was longer than 20 days.(6)The number of cases: The minimum of case number was 10 and the maxnum was 578. 74(67.89%) outbreaks had more than 50 cases.(7) Attact rate: The mininum of attack rate was 0.24% and the maxnum was 60%. The attact rate of 38(27.52%) outbreaks was more than 10%.3. Timing of intervention: The duration of influenza outbreak in school was related to school scale, the type of virus, intervention time and intervention scale. The cases number of school flu outbreak was related with the type of virus, school scale and intervention scale.4.Intervention method:The order of utilization rates of various means of intervention from high to low was isolation, treatment, health education, ventilation, morning check, disinfection, drug prophylaxis, school closure and vaccines. For all of the outbreaks, intervention method for cases(isolation+ treatment of patients) was used. The proportion of intervention combined with 5 or more methods was larger than 94.4%. Without the consideration of cost, generally speaking, more intervention methods showed the better results. Vaccine before outbreak was more effective than vaccine after outbreak. The intervention method combined with 9(treatment + isolation+ disinfection + ventilation + health education + morning check + drug prophylaxis + school closure + 50% vaccine before outbreak) was the most ideal intervention method. The intervention measure combined of 6(treatment + isolation+ disinfection + ventilation + health education + morning check) could shorten the duration of outbreak compared with measure combined of 5(treatment + isolation+ ventilation + health education + morning check). The effect of method combined of 7(treatment + isolation+ disinfection + ventilation + health education + morning check + drug prophylaxis) was similar with that of measure combined of 8(treatment + isolation+ disinfection + ventilation + health education + morning check + drug prophylaxis + school closure). With the consideration of cost, less intervention method showed the lower cost-effectiveness ratio. However, the cost-effectiveness ratio of method combined of 8(treatment + isolation+ disinfection + ventilation + health education + morning check + drug prophylaxis + school closure) was lower than that of measure combined of 7(treatment + isolation+ disinfection + ventilation + health education + morning check + drug prophylaxis).Conclusion: The optimal intervention time for school flu outbreak was 5 days or less, and the optimal scale of intervention was between 16 and 30 cases. Without the consideration of cost, the most ideal intervention method was method combined of 9(treatment + isolation+ disinfection + ventilation + health education + morning check + drug prophylaxis + school closure + 50% vaccine before outbreak).With the consideration of cost, the optimal intervention method was method combined of 5(treatment + isolation+ ventilation + health education + morning check). On average, the optimal intervention method for school flu outbreak was method combined of 6(treatment + isolation+ disinfection + ventilation + health education + morning check).