A modelling framework to assess the likely effectiveness of facemasks in combination with 'lock-down' in managing the COVID-19 pandemic
A modelling framework to assess the likely effectiveness of facemasks in combination with 'lock-down' in managing the COVID-19 pandemic
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DOI：
10.1098/rspa.2020.0376
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发表时间：
2020-06-24
影响因子：
3.5
通讯作者：
Colvin, John
中科院分区：
文献类型：
--
作者：
Stutt, Richard O. J. H.;Retkute, Renata;Colvin, John
COVID-19的特征是感染性症状前阶段，新感染者可能会在不知情的情况下感染他人。我们感兴趣的是，口罩作为一种非药物干预措施可以带来什么好处，特别是在高科技干预措施（如使用移动的应用程序进行接触者追踪或通过分子检测进行快速病例检测）不可持续的情况下。在这里，我们报告了两个数学模型的结果，并表明公众使用口罩可以为减少COVID-19大流行的影响做出重大贡献。我们的目的是提供一个简单的建模框架，以研究当公众戴口罩时，无论是否有强制的“封锁”期，COVID-19疫情的动态。我们的研究结果说明了一些合理的值参数范围描述的流行病学过程和机械性能的口罩，在没有目前的测量这些值。我们发现，当公众一直使用口罩时（不仅仅是从症状首次出现时），有效繁殖数R-e可以降低到1以下，从而减轻流行病的传播。在某些情况下，当实施封锁期并100%使用口罩时，疾病传播会大大减少，第二波和第三波被压平，疫情得到控制。即使假设面罩在捕获呼出的病毒接种物时仅具有50%的有效性，而吸入时具有相同或更低的效率，也会发生这种效果。公众使用口罩被认为是无效的，因为佩戴者可能会更频繁地触摸他们的脸，从而增加感染COVID-19的可能性。为了完整起见，我们的模型表明，即使在佩戴者面临更大风险的情况下，面罩的采用也会带来人群层面的益处。在撰写本文时，许多国家还没有建议公众使用口罩，但苏格兰刚刚宣布了佩戴口罩的建议。我们的研究结果显示，即使在第一个封锁期开始后才开始使用口罩，仍可以通过降低进一步发生COVID-19疫情的风险来累积收益。我们研究的影响，不同的利率的面罩采用没有锁定期，并表明，即使在较低水平的采用，利益累积到面罩佩戴者。这些分析可以解释为什么一些国家的公众使用口罩的比例约为100%，但COVID-19传播率和相关死亡率却显著降低。我们的结论是，公众使用口罩，与物理距离或封锁期结合使用，可能是管理COVID-19大流行和重新开放经济活动的可接受方式。这些结果与发达国家和发展中国家有关，这些国家的大量人口资源匮乏，但自制有效的口罩是可能的。从我们的分析中得出的一个关键信息，以帮助广泛采用口罩将是：“我的面具保护你，你的面具保护我”。
COVID-19 is characterized by an infectious pre-symptomatic period, when newly infected individuals can unwittingly infect others. We are interested in what benefits facemasks could offer as a non-pharmaceutical intervention, especially in the settings where high-technology interventions, such as contact tracing using mobile apps or rapid case detection via molecular tests, are not sustainable. Here, we report the results of two mathematical models and show that facemask use by the public could make a major contribution to reducing the impact of the COVID-19 pandemic. Our intention is to provide a simple modelling framework to examine the dynamics of COVID-19 epidemics when facemasks are worn by the public, with or without imposed 'lock-down' periods. Our results are illustrated for a number of plausible values for parameter ranges describing epidemiological processes and mechanistic properties of facemasks, in the absence of current measurements for these values. We show that, when facemasks are used by the public all the time (not just from when symptoms first appear), the effective reproduction number, R-e, can be decreased below 1, leading to the mitigation of epidemic spread. Under certain conditions, when lock-down periods are implemented in combination with 100% facemask use, there is vastly less disease spread, secondary and tertiary waves are flattened and the epidemic is brought under control. The effect occurs even when it is assumed that facemasks are only 50% effective at capturing exhaled virus inoculum with an equal or lower efficiency on inhalation. Facemask use by the public has been suggested to be ineffective because wearers may touch their faces more often, thus increasing the probability of contracting COVID-19. For completeness, our models show that facemask adoption provides population-level benefits, even in circumstances where wearers are placed at increased risk. At the time of writing, facemask use by the public has not been recommended in many countries, but a recommendation for wearing face-coverings has just been announced for Scotland. Even if facemask use began after the start of the first lock-down period, our results show that benefits could still accrue by reducing the risk of the occurrence of further COVID-19 waves. We examine the effects of different rates of facemask adoption without lock-down periods and show that, even at lower levels of adoption, benefits accrue to the facemask wearers. These analyses may explain why some countries, where adoption of facemask use by the public is around 100%, have experienced significantly lower rates of COVID-19 spread and associated deaths. We conclude that facemask use by the public, when used in combination with physical distancing or periods of lock-down, may provide an acceptable way of managing the COVID-19 pandemic and re-opening economic activity. These results are relevant to the developed as well as the developing world, where large numbers of people are resource poor, but fabrication of home-made, effective facemasks is possible. A key message from our analyses to aid the widespread adoption of facemasks would be: 'my mask protects you, your mask protects me'.