Nishiura Hiroshi, Ejima Keisuke, Mizumoto Kenji, Nakaoka Shinji, Inaba Hisashi, Imoto Seiya, Yamaguchi Rui, Saito Masaya M
Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 1130033, Japan.
Theor Biol Med Model. 2014 Jan 21;11:5. doi: 10.1186/1742-4682-11-5.
There has been a variation in published opinions toward the effectiveness of school closure which is implemented reactively when substantial influenza transmissions are seen at schools. Parameterizing an age-structured epidemic model using published estimates of the pandemic H1N1-2009 and accounting for the cost effectiveness, we examined if the timing and length of school closure could be optimized.
Age-structured renewal equation was employed to describe the epidemic dynamics of an influenza pandemic. School closure was assumed to take place only once during the course of the pandemic, abruptly reducing child-to-child transmission for a fixed length of time and also influencing the transmission between children and adults. Public health effectiveness was measured by reduction in the cumulative incidence, and cost effectiveness was also examined by calculating the incremental cost effectiveness ratio and adopting a threshold of 1.0 × 10⁷ Japanese Yen/life-year.
School closure at the epidemic peak appeared to yield the largest reduction in the final size, while the time of epidemic peak was shown to depend on the transmissibility. As the length of school closure was extended, we observed larger reduction in the cumulative incidence. Nevertheless, the cost effectiveness analysis showed that the cost of our school closure scenario with the parameters derived from H1N1-2009 was not justifiable. If the risk of death is three times or greater than that of H1N1-2009, the school closure could be regarded as cost effective.
There is no fixed timing and duration of school closure that can be recommended as universal guideline for different types of influenza viruses. The effectiveness of school closure depends on the transmission dynamics of a particular influenza virus strain, especially the virulence (i.e. the infection fatality risk).
对于学校关闭的有效性，已发表的观点存在差异。学校关闭是在学校出现大量流感传播时被动实施的。我们使用已发表的2009年甲型H1N1流感估计值对年龄结构的流行模型进行参数化，并考虑成本效益，研究了学校关闭的时间和时长是否可以优化。
采用年龄结构更新方程来描述流感大流行的流行动态。假设在大流行过程中学校仅关闭一次，在固定时长内突然减少儿童之间的传播，同时也影响儿童与成人之间的传播。通过累积发病率的降低来衡量公共卫生效果，并通过计算增量成本效益比并采用1.0×10⁷日元/生命年的阈值来检验成本效益。
在疫情高峰时关闭学校似乎能使最终规模的减少幅度最大，而疫情高峰时间显示取决于传播性。随着学校关闭时长的延长，我们观察到累积发病率的降低幅度更大。然而，成本效益分析表明，根据2009年甲型H1N1流感得出的参数进行学校关闭的情景成本是不合理的。如果死亡风险是2009年甲型H1N1流感的三倍或更高，学校关闭可被视为具有成本效益。
不存在可作为不同类型流感病毒通用指南推荐的固定学校关闭时间和时长。学校关闭的有效性取决于特定流感病毒株的传播动态，尤其是毒力（即感染致死风险）。
