Since the beginning of the COVID-19 pandemic, there has been intense debate over SARS-CoV-2’s mode of transmission and appropriate personal protective equipment for health care workers in low-risk settings. The objective of this review is to identify and appraise the available evidence (clinical trials and laboratory studies on masks and respirators, epidemiological studies, and air sampling studies), clarify key concepts and necessary conditions for airborne transmission, and shed light on knowledge gaps in the field. We find that, except for aerosol-generating procedures, the overall data in support of airborne transmission—taken in its traditional definition (long-distance and respirable aerosols)—are weak, based predominantly on indirect and experimental rather than clinical or epidemiological evidence. Consequently, we propose a revised and broader definition of “airborne,” going beyond the current droplet and aerosol dichotomy and involving short-range inhalable particles, supported by data targeting the nose as the main viral receptor site. This new model better explains clinical observations, especially in the context of close and prolonged contacts between health care workers and patients, and reconciles seemingly contradictory data in the SARS-CoV-2 literature. The model also carries important implications for personal protective equipment and environmental controls, such as ventilation, in health care settings. However, further studies, especially clinical trials, are needed to complete the picture.

中文翻译：

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SARS-CoV-2 和低风险环境中的医护人员保护：传播模式回顾和涉及可吸入颗粒的新型空气传播模型

自 COVID-19 大流行开始以来，关于 SARS-CoV-2 的传播方式以及低风险环境中医护人员的适当个人防护设备一直存在激烈争论。本次审查的目的是识别和评估现有证据（关于口罩和呼吸器的临床试验和实验室研究、流行病学研究和空气采样研究），澄清空气传播的关键概念和必要条件，并阐明空气传播的知识差距。场。我们发现，除了气溶胶产生程序外，支持空气传播的总体数据（按照其传统定义（长距离和可吸入气溶胶））很薄弱，主要基于间接和实验证据，而不是临床或流行病学证据。因此，我们提出了对“空气传播”的修订和更广泛的定义，超越了目前的飞沫和气溶胶二分法，并涉及短程可吸入颗粒，并得到了以鼻子作为主要病毒受体部位的数据的支持。这种新模型更好地解释了临床观察结果，特别是在医护人员和患者之间密切和长期接触的背景下，并协调了 SARS-CoV-2 文献中看似矛盾的数据。该模型还对医疗机构中的个人防护设备和环境控制（例如通风）具有重要影响。然而，还需要进一步的研究，特别是临床试验来完成这一切。