WHO回应239名专家公开信 | 现在是解决COVID-19空中传播问题的时候了

Original 消毒学进展 RJ感控宝典 2022-10-12

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导读

据《纽约时报》7月5日首先报道，来自全球239名科学家向世界卫生组织（WHO）发出呼吁，要求其修改关于SARS-CoV-2空气传播的指南。该专家信和名单已于7月6日发表在《Clinical Infectious Diseases》杂志上。WHO发言人Tarik Jasarevic同日通过电子邮件回应：我们知道这篇文章，并正在与我们的技术专家审查其内容。7月7日WHO 负责COVID-19疫情应对的技术负责人Maria Van Kerkhove在新闻发布会上表示，我们一直在讨论将空气传播和气溶胶传播作为新冠肺炎传播方式之一的可能性。以下是专家信原文、翻译和专家名单。

提示：感兴趣的可以参与文章中部的投票。

现在是解决COVID-19空气传播问题的时候了

It is Time to Address Airborne Transmission of COVID-19

Lidia Morawska1,*, Donald K. Milton2

1 International Laboratory for Air Quality and Heath, WHO Collaborating Centre, Queensland University of Technology, 2 George Street, Brisbane, QLD 4001 Australia. Email: l.morawska@qut.edu.au

2 Institute for Applied Environmental Health, University of Maryland School of Public Health, 255 Campus Dr, College Park, Maryland, USA. Email: dmilton@umd.edu

Corresponding author: Lidia Morawska

We appeal to the medical community and to the relevant national and international bodies to recognize the potential for airborne spread of COVID-19. There is significant potential for inhalation exposure to viruses in microscopic respiratory droplets (microdroplets) at short to medium distances (up to several meters, or room scale), and we are advocating for the use of preventive measures to mitigate this route of airborne transmission.

我们呼吁医学界、相关国家和国际机构认识到COVID-19通过空气传播的可能性。在短距离至中距离(可达数米或房间内)条件下，暴露于微小呼吸道飞沫（微小液滴）而吸入病毒的可能性很大，我们主张采取相关预防控制措施，以降低空气传播风险。

Studies by the signatories and other scientists have demonstrated beyond any reasonable doubt that viruses are released during exhalation, talking, and coughing in microdroplets small enough to remain aloft in air and pose a risk of exposure at distances beyond 1 to 2 m from an infected individual (see e.g. [1-4]). For example, at typical indoor air velocities [5], a 5 μm droplet will travel tens of meters, much greater than the scale of a typical room, while settling from a height of 1.5 m to the floor. Several retrospective studies conducted after the SARS-CoV-1 epidemic demonstrated that airborne transmission was the most likely mechanism explaining the spatial pattern of infections e.g. [6].Retrospective analysis has shown the same for SARS-CoV-2 [7-10]. In particular, a study in their review of records from a Chinese restaurant, observed no evidence of direct or indirect contact between the three parties [10]. In their review of video records from the restaurant, they observed no evidence of direct or indirect contact between the three parties. Many studies conducted on the spread of other viruses, including respiratory syncytial virus (RSV) [11], Middle East Respiratory Syndrome coronavirus (MERS-CoV) [8], and influenza [2,4], show that viable airborne viruses can be exhaled [2] and/or detected in the indoor environment of infected patients [11-12]. This poses the risk that people sharing such environments can potentially inhale these viruses, resulting in infection and disease. There is every reason to expect that SARS-CoV-2 behaves similarly, and that transmission via airborne microdroplets [10,13] is an important pathway. Viral RNA associated with droplets smaller than 5 μm has been detected in air [14], and the virus has been shown to maintain infectivity in droplets of this size [9]. Other viruses have been shown to survive equally well, if not better, in aerosols compared to droplets on a surface [15].

签名者和其他科学家的研究已经证明，毫无疑问，病毒会在呼气、说话和咳嗽的过程中以微小液滴的形式释放出来，这些微小的液滴足以保持在空中，在超过感染者1到2米以外的距离产生暴露风险。在典型的室内空气流速下，一个5um的液滴会移动数十米，并从1.5米的高度沉降到地面，微小液滴移动的距离比一个典型房间尺寸大得多。SARS-CoV-1流行后进行的几项回顾性研究表明，空气传播机制最有可能解释其空间感染的模式。SARS-CoV-2回顾性分析也表明，该病毒也是如此。特别值得一提的是，在对一家中国餐馆的调查中发现，没有证据表明三方有直接或间接的接触。在查看餐厅的视频记录时，没有发现三方有直接或间接接触的证据。呼吸道合胞病毒(RSV)、中东呼吸综合征冠状病毒(MERS-CoV)、流感等其他病毒的传播研究表明，活病毒可通过呼吸道排出到空气中，并/或在感染者室内环境中检测到，暴露于同一环境的人可能存在吸入这些病毒的风险，从而导致感染和疾病。我们有充分的理由相信SARS-CoV-2具有类似的特点，而通过空气中的微滴传播是一个重要途径。在空气中已检测到与小于5um的微小液滴相关的病毒RNA，并且已证明该病毒在这种大小的液滴中会保持感染性，其他病毒也已经被证明在气溶胶中的存活能力与在表面飞沫中存活能力相当。

The current guidance from numerous international and national bodies focuses on hand washing, maintaining social distancing, and droplet precautions. Most public health organizations, including the World Health Organization (WHO) [16], do not recognize airborne transmission except for aerosol-generating procedures performed in healthcare settings. Hand washing and social distancing are appropriate, but in our view, insufficient to provide protection from virus-carrying respiratory microdroplets released into the air by infected people. This problem is especially acute in indoor or enclosed environments, particularly those that are crowded and have inadequate ventilation [17] relative to the number of occupants and extended exposure periods (as graphically depicted in Figure 1). For example, airborne transmission appears to be the only plausible explanation for several superspreading events investigated which occurred under such conditions e.g. [10], and others where recommended precautions related to direct droplet transmissions were followed.

目前许多国家和国际组织的指南将重点放在洗手、保持社交距离和飞沫传播预防上，大多数公共卫生组织，包括世界卫生组织(WHO)，不认可空气传播，仅认可在医疗机构中实施产生气溶胶操作程序时会发生空气传播。洗手和保持社交距离是正确的，但我们认为，这不足以保护人们不受感染者释放到空气中的携带病毒的呼吸道微小液滴的伤害。这一问题在室内或封闭环境中尤其严重，特别是那些拥挤、通风不良和长时间暴露的环境（如图1）。空气传播似乎是在这种情况下，以及在其他情况下采取了飞沫传播有关的预防措施，而发生的几次超级传播事件的唯一合理解释。

图注：呼吸道微小液滴在(a)通风不足和(b)通风充足的室内环境中的分布

The evidence is admittedly incomplete for all the steps in COVID-19 microdroplet transmission, but it is similarly incomplete for the large droplet and fomite modes of transmission. The airborne transmission mechanism operates in parallel with the large droplet and fomite routes, e.g. [16] that are now the basis of guidance. Following the precautionary principle, we must address every potentially important pathway to slow the spread of COVID-19. The measures that should be taken to mitigate airborne transmission risk include:

Provide sufficient and effective ventilation (supply clean outdoor air, minimize recirculating air) particularly in public buildings, workplace environments, schools, hospitals, and aged care homes.

Supplement general ventilation with airborne infection controls such as local exhaust, high efficiency air filtration, and germicidal ultraviolet lights.

Avoid overcrowding, particularly in public transport and public buildings.

诚然，COVID-19微小液滴传播的证据还不完整，但较大飞沫和污染物传播方式的证据同样不完整。同时考虑空气传播机制与飞沫传播和污染物传播，应是目前指南制订的基础。根据预防的基本原则，我们必须考虑减缓COVID-19传播的每一个可能的重要途径。为降低空气传播风险采取，采取的预防控制措施应包括：

在公共场所、工作场所、学校、医院和养老院，提供充分且有效的通风(提供清洁的室外空气，减少室内循环空气)。

用局部排气、高效空气过滤和紫外线杀菌灯等空气感染控制措施补充普通的通风。

避免过度拥挤，特别是在公共交通工具和公共场所。

Such measures are practical and often can be easily implemented; many are not costly. For example, simple steps such as opening both doors and windows can dramatically increase air flow rates in many buildings. For mechanical systems, organizations such as ASHRAE (the American Society of Heating, Ventilating, and Air-Conditioning Engineers) and REHVA (the Federation of European Heating, Ventilation and Air Conditioning Associations) have already provided guidelines based on the existing evidence of airborne transmission. The measures we propose offer more benefits than potential downsides, even if they can only be partially implemented.

这些措施是切实可行的，往往很容易执行，很多并不昂贵。例如，一些简单的方法，如打开门窗，可以显著增加许多建筑物的空气流量。对于机械通风系统，诸如ASHRAE(美国供暖、通风和空调工程师协会)和REHVA(欧洲供暖、通风和空调协会联合会)等组织已经根据现有的空气传播证据提供了指导方针。我们提出的措施，即使只能部分实施，也会带来更多的好处，而不是潜在的负面影响。

It is understood that there is not as yet universal acceptance of airborne transmission of SARS-CoV2; but in our collective assessment there is more than enough supporting evidence so that the precautionary principle should apply. In order to control the pandemic, pending the availability of a vaccine, all routes of transmission must be interrupted.

据了解，SARS-CoV2的空中传播尚未得到普遍接受，但在我们的集体评估中，已有足够多的证据，支持应当采取空气传播预防控制措施。为了控制大流行，在获得疫苗之前，必须阻断所有传播途径。

We are concerned that the lack of recognition of the risk of airborne transmission of COVID-19 and the lack of clear recommendations on the control measures against the airborne virus will have significant consequences: people may think that they are fully protected by adhering to the current recommendations, but in fact, additional airborne interventions are needed for further reduction of infection risk.

我们担心，对COVID-19空气传播的风险认识不足，和对空气传播防控指南的缺乏，将会产生严重的后果:人们会认为遵照当前的指南，他们已得到完全保护，但事实上，他们需要额外的干预措施以进一步降低感染的风险。

This matter is of heightened significance now, when countries are re-opening following lockdowns - bringing people back to workplaces and students back to schools, colleges, and universities. We hope that our statement will raise awareness that airborne transmission of COVID-19 is a real risk and that control measures, as outlined above, must be added to the other precautions taken, to reduce the severity of the pandemic and save lives.

现在，这一问题具有更大的紧迫性，因为各国在关闭后重新开放，让人们重新回到工作场所，让学生们重新回到学校。我们希望，我们的声明能提高人们的认识，即COVID-19空气传播是一种切实存在的风险，必须在采取其他预防措施的基础上，增加上述空气传播预防控制措施，以减轻大流行的严重程度，挽救更多生命。

Disclaimer: The views and opinions expressed in this article are those of the authors and do not necessarily reflect the official policy or position of any agency/institution.

免责声明:本文所表达的观点和意见仅为作者个人观点，并不代表任何机构或机构的官方政策或立场。

Acknowledgment

Together with the authors, 239 scientists support this Commentary, and their affiliations and contact details are listed in the Supplementary.

致谢

239名科学家和作者一起支持这一呼吁，他们的单位和联系方式在补充文件中列出。

6月5日，本公众号对空气传播途径的态度进行了一次调查（详见顶刊PNAS | 空气传播为COVID-19的主要传播途径），截止本文发稿投票结果如下：

现在，您的态度如何？欢迎再次参与下方投票。

239名科学家来自32个国家不同的科学和工程领域，包括病毒学、气溶胶物理学、流动力学、暴露和流行病学、医学和建筑工程。

姓名、单位和联系方式如下：

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