Guidelines from the CDC and the WHO recommend the wearing of face masks to prevent the spread of coronavirus (CoV) disease 2019 (COVID-19); however, the protective efficiency of such masks against airborne transmission of infectious severe acute respiratory syndrome CoV-2 (SARS-CoV-2) droplets/aerosols is unknown. Here, we developed an airborne transmission simulator of infectious SARS-CoV-2-containing droplets/aerosols produced by human respiration and coughs and assessed the transmissibility of the infectious droplets/aerosols and the ability of various types of face masks to block the transmission. We found that cotton masks, surgical masks, and N95 masks all have a protective effect with respect to the transmission of infective droplets/aerosols of SARS-CoV-2 and that the protective efficiency was higher when masks were worn by a virus spreader. Importantly, medical masks (surgical masks and even N95 masks) were not able to completely block the transmission of virus droplets/aerosols even when completely sealed. Our data will help medical workers understand the proper use and performance of masks and determine whether they need additional equipment to protect themselves from infected patients.

中文翻译：

---

口罩在预防SARS-CoV-2机载传播中的功效

CDC和WHO的指南建议戴口罩以防止2019年冠状病毒（CoV）疾病的传播（COVID-19）; 但是，这种口罩对传染性严重急性呼吸系统综合症CoV-2（SARS-CoV-2）小滴/气溶胶在空气中传播的防护作用尚不清楚。在这里，我们开发了一种由人的呼吸和咳嗽产生的含有传染性SARS-CoV-2的小滴/气溶胶的机载传播模拟器，并评估了这种传染性小滴/气溶胶的传播能力以及各种口罩阻止传播的能力。我们发现，棉口罩，外科口罩，N95和N95口罩均对SARS-CoV-2感染性小滴/气溶胶的传播具有保护作用，并且当病毒传播者配戴口罩时，保护效率更高。重要的是，即使完全密封，医用口罩（手术口罩，甚至是N95口罩）也不能完全阻止病毒飞沫/气溶胶的传播。我们的数据将帮助医务人员了解口罩的正确使用方法和性能，并确定他们是否需要其他设备来保护自己免受感染患者的侵害。