Mizumoto Kenji, Nishiura Hiroshi, Yamamoto Taro
School of Public Health, The University of Hong Kong, 100 Cyberport Road, Pokfulam, Hong Kong, China.
Theor Biol Med Model. 2013 Jan 16;10:4. doi: 10.1186/1742-4682-10-4.
During the very early stage of the 2009 pandemic, mass chemoprophylaxis was implemented as part of containment measure. The purposes of the present study were to systematically review the retrospective studies that investigated the effectiveness of antiviral prophylaxis during the 2009 pandemic, and to explicitly estimate the effectiveness by employing a mathematical model.
A systematic review identified 17 articles that clearly defined the cases and identified exposed individuals based on contact tracing. Analysing a specific school-driven outbreak, we estimated the effectiveness of antiviral prophylaxis using a renewal equation model. Other parameters, including the reproduction number and the effectiveness of antiviral treatment and school closure, were jointly estimated.
Based on the systematic review, median secondary infection risks (SIRs) among exposed individuals with and without prophylaxis were estimated at 2.1% (quartile: 0, 12.2) and 16.6% (quartile: 8.4, 32.4), respectively. A very high heterogeneity in the SIR was identified with an estimated I2 statistic at 71.8%. From the outbreak data in Madagascar, the effectiveness of mass chemoprophylaxis in reducing secondary transmissions was estimated to range from 92.8% to 95.4% according to different model assumptions and likelihood functions, not varying substantially as compared to other parameters.
Only based on the meta-analysis of retrospective studies with different study designs and exposure settings, it was not feasible to estimate the effectiveness of antiviral prophylaxis in reducing transmission. However, modelling analysis of a single outbreak successfully yielded an estimate of the effectiveness that appeared to be robust to model assumptions. Future studies should fill the data gap that has existed in observational studies and allow mathematical models to be used for the analysis of meta-data.
在2009年大流行的极早期阶段，实施了大规模化学预防作为防控措施的一部分。本研究的目的是系统回顾调查2009年大流行期间抗病毒预防效果的回顾性研究，并通过数学模型明确估计其效果。
一项系统回顾确定了17篇文章，这些文章明确界定了病例，并通过接触者追踪确定了暴露个体。通过分析一次特定的学校引发的疫情，我们使用更新方程模型估计了抗病毒预防的效果。同时联合估计了其他参数，包括繁殖数、抗病毒治疗的效果和学校关闭的效果。
基于系统回顾，接受预防和未接受预防的暴露个体中的中位继发感染风险（SIR）分别估计为2.1%（四分位数：0，12.2）和16.6%（四分位数：8.4，32.4）。发现SIR存在非常高的异质性，估计的I²统计量为71.8%。根据马达加斯加的疫情数据，根据不同的模型假设和似然函数，大规模化学预防在减少继发传播方面的效果估计在92.8%至95.4%之间，与其他参数相比变化不大。
仅基于对具有不同研究设计和暴露情况设置的回顾性研究进行荟萃分析，估计抗病毒预防在减少传播方面的效果是不可行的。然而，对一次单一疫情的模型分析成功得出了一个效果估计值，该估计值似乎对模型假设具有稳健性。未来的研究应填补观察性研究中存在的数据空白，并允许使用数学模型进行元数据分析。
