N95口罩能否在消毒后复用？翻译一篇research letter
最近有不少朋友询问口罩消毒的事情，于是我翻到了这篇2020年9月发表在Emerging Infectious Diseases上的research letter。由于它给出了结论和比较容易执行的方案，遂搬运。仅提供一种可能性，以应对（可能发生的）N95短缺。一次性使用医用口罩及医用外科口罩请勿复用。
愿意啃论文的朋友，可以到https://www.zhihu.com/question/367683843?utm_id=0看看其他类似研究，其中有一篇指出常见消毒方法可能破坏熔喷材料结构，但似乎与其他论文意见存在冲突。
我本人不是医学/概率学/统计学专业，翻译可能存在错误，欢迎发现错误的朋友们指出；也欢迎持有不同观点的朋友带着论据来交流。
请注意，这篇letter只测试了消毒方法生效时长和对N95口罩熔喷材料过滤性能的影响，没有测试对呼气阀、鼻梁条、头带等其他附件的影响。建议每次消毒后做一次定性的适合性试验以确保N95口罩功能的完整性！
有论文用市面上能随便买到的工具“教你在家做定性适合性试验（QLFT）”，生肉，我正在搬。能者先啃：https://doi.org/10.1017/dmp.2020.352
术语首次出现时会用括号写出缩写，再出现会直接用缩写（懒）；译文中由译者添加的括号是方括号，在原文中就有的括号是圆括号。
以下是全文搬运+正文翻译：
对N95呼吸器消毒的有效性，及应对新冠病毒的复用
Effectiveness of N95 Respirator Decontamination and Reuse against SARS-CoV-2 Virus
Robert J. Fischer, Dylan H. Morris, Neeltje van Doremalen, Shanda Sarchette, M. Jeremiah Matson, Trenton Bushmaker, Claude Kwe Yinda, Stephanie N. Seifert, Amandine Gamble, Brandi N. Williamson, Seth D. Judson, Emmie de Wit, James O. Lloyd-Smith, Vincent J. Munste
DOI: https://doi.org/10.3201/eid2609.201524
摘要：冠状病毒疫情大流行引起了全球范围的N95呼吸器短缺。我们选用了四种消毒方法，分析了它们对新冠病毒的灭活能力和对呼吸器功能的影响。结果指出，N95呼吸器可以在消毒后复用，前提是呼吸器的适合性及气密性保持完好。
The coronavirus pandemic has created worldwide shortages of N95 respirators. We analyzed 4 decontamination methods for effectiveness in deactivating severe acute respiratory syndrome coronavirus 2 virus and effect on respirator function. Our results indicate that N95 respirators can be decontaminated and reused, but the integrity of respirator fit and seal must be maintained.
史无前例的冠状病毒病大流行造成了世界范围内个人防护用品【personal protective equipment，PPE】的短缺，尤其是如N95呼吸器这类的呼吸系统防护用具(1)。新冠病毒在医院环境的传播时有发生，大量院内传播案例凸显出医护工作者【面对院感】的脆弱性(2)。新冠病毒在环境中的稳定性【environmental stability】造成了对迅速、有效的消毒方法的迫切需求。
The unprecedented pandemic of coronavirus disease has created worldwide shortages of personal protective equipment, in particular respiratory protection such as N95 respirators (1). Transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) occurs frequently in hospital settings; numerous reported cases of nosocomial transmission highlight the vulnerability of healthcare workers (2). The environmental stability of SARS-CoV-2 virus underscores the need for rapid and effective decontamination methods.
一般来说，N95呼吸器本该在使用一次后即丢弃，不过大量文献中都包含对N95呼吸器消毒以杀灭细菌芽孢【bacterial spores】、细菌或呼吸道病毒（比如甲流病毒）(3-6)的内容。有效杀灭病原体的方法包括紫外线、环氧乙烷、汽化双氧水【vaporized hydrogen peroxide，VHP】、γ射线、臭氧和干热(A. Cramer et al., unpub data, https://doi.org/10.1101/2020.03.28.20043471) (3–6)。然而，针对这些消毒方法对N95呼吸器的过滤效率及适合性的影响，尚未有太多深入研究。有报告显示，上述的消毒方法确实会对N95呼吸器的过滤效率和适合性产生影响。(7; 附录：https://wwwnc.cdc.gov/EID/ article/26/9/20-1524-App1.pdf).
In general, N95 respirators are designed for one use before disposal. Extensive literature is available for decontaminating N95 respirators of either bacterial spores, bacteria, or respiratory viruses (e.g. influenza A virus) (3–6). Effective inactivation methods for these pathogens and surrogates include UV light, ethylene oxide, vaporized hydrogen peroxide (VHP), gamma irradiation, ozone, and dry heat (A. Cramer et al., unpub data, https://doi.org/10.1101/2020.03.28.20043471) (3–6). The filtration efficiency and fit of N95 respirators has been less well explored, but reports suggest that both filtration efficiency and N95 respirator fit can be affected by the decontamination method used (7; Appendix, https://wwwnc.cdc.gov/EID/ article/26/9/20-1524-App1.pdf).
我们选用了4种消毒方法——紫外线（波长260-285纳米）、70℃干热、70%酒精和汽化双氧水【VHP】，分析了它们杀灭新冠病毒的能力和对N95呼吸器功能的影响。新冠病毒初始接种的循环阈值【Ct值】*为20-22，接近从人的上呼吸道及下呼吸道取样得来的数值。我们将每一种消毒方法在N95织物【N95 filter fabric】上的消毒速率，同该消毒方法在不锈钢上的消毒速率作比较。在每一轮消毒并佩戴两小时后，我们采用定量的适合性试验【QNFT】评估N95呼吸器的过滤效果，连续做三轮(附录)。VHP和酒精在N95及不锈钢上都有极快的消毒速率（图，panel A）；紫外线在不锈钢上的消毒速率很快，但在N95织物上慢得多，推测与织物多孔的特性有关；干热则相反，在N95上的消毒速率比在不锈钢上快。
（*译者：记得核酸检测的“Ct值”吗？就是它）
We analyzed 4 different decontamination methods, UV light (260–285 nm), 70ºC dry heat, 70% ethanol, and VHP, for their ability to reduce contamination with infectious SARS-CoV-2 and their effect on N95 respirator function. The starting inoculum of SARS-CoV-2 has cycle threshold values of 20–22, similar to those observed in samples obtained from the upper and lower respiratory tract in humans. For each of the decontamination methods, we compared the normal inactivation rate of SARS-CoV-2 virus on N95 filter fabric to that on stainless steel. Using quantitative fit testing, we measured the filtration performance of N95 respirators after each decontamination run and 2 hours of wear, for 3 consecutive decontamination and wear sessions (Appendix). VHP and ethanol yielded extremely rapid inactivation both on N95 and on stainless steel (Figure, panel A). UV light inactivated SARS-CoV-2 virus rapidly from steel but more slowly on N95 fabric, probable because of its porous nature. Heat caused more rapid inactivation on N95 than on steel; inactivation rates on N95 were comparable to UV.
图。4种方式消毒N95呼吸器的结果。
A) 新冠病毒失活速率（附录：https://wwwnc.cdc.gov/EID/article/26/9/20-1524-App1.pdf）。“点”是三次消毒后平均存活滴度【mean viable titer】的估计值，“圆”是平均存活滴度的后验中值，“粗条”是68% credible interval【这怎么翻？】，“细条”是95% credible interval。直线表示病毒滴度随时间衰减的程度，根据指数衰减曲线（负斜率）的联合后验分布和截距（初始病毒滴度），随机重复50次后生成。任意一次试验中未出现阳性孔的用三角形标记在每次试验近似检出限【approximate single-replicate LOD】上，用来指示低于检出限【LOD】的值可能置于的区间。黑色点虚线表示近似检出限：100.5 TCID50/mL。在酒精和干热针对不锈钢消毒的图中，为了避免过度绘制，t=0时在LOD上的点有轻微向上和向左移动。
B）消毒并佩戴两小时，重复三轮后，口罩的QNFT结果。每种消毒方法的6次实验的数据（小圆和小三角），以及估计的适合因数中值（大圆）、适合因数的68%区间（粗条）、95%区间（细条）如图所示。适合因数是口罩外颗粒物浓度与口罩内浓度的比值，用于衡量过滤能力，由测量的机器报出数值。
（译者：如果你看翻译看得头大，请相信我，我看原文也是这种感觉。）
Figure. Results of decontamination of N95 respirators by 4 different methods. A) Inactivation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus (Appendix, https://wwwnc.cdc.gov/EID/article/26/9/20-1524-App1.pdf). Points indicate estimated mean viable titer across 3 replicates, circles the posterior median estimate of the mean, thick bars a 68% credible interval, and thin bars a 95% credible interval. Lines show predicted decay of virus titer over time and were generated by 50 random draws/replicate from the joint posterior distribution of the exponential decay rate (negative of the slope) and intercept (initial virus titer). Time points with no positive wells for any replicate are plotted as triangles at the approximate single-replicate LOD to indicate a plausible range of sub-LOD values. Black dotted line shows approximate LOD: 100.5 TCID50/mL media. Points at the LOD and at t = 0 for ethanol and heat methods applied to steel are offset slightly up and to the left to avoid overplotting. B) Mask integrity quantitative fit testing results after decontamination and 2 hours of wear for 3 consecutive runs. Data from 6 individual replicates (small circles and triangles) for each treatment are shown, in addition to estimated median fit factor (large circles), 68% range of underlying fit factors (thick bars), and 95% range (thin bars). Fit factors are a measure of filtration performance, the ratio of the concentration of particles outside the mask to the concentration inside. The measurement machine reports values
QNFT显示：4种消毒方法的单轮消毒都不会显著降低N95呼吸器的过滤能力*（图，panel B），而后续的消毒中，酒精和干热会大幅降低N95的过滤能力，其中干热的表现略好于酒精。经VHP和紫外线消毒的口罩相较于对照组，在两轮消毒后仍保持着差不多【comparable】的过滤能力，三轮消毒后的表现“勉强能用”【acceptable】。
（*译者：仍有下降，酒精和干热消毒后的N95有小概率通不过适合性试验，见图）
Quantitative fit tests showed that the filtration performance of the N95 respirator was not markedly reduced after a single decontamination for any of the 4 decontamination methods (Figure, panel B). Subsequent rounds of decontamination caused sharp drops in filtration performance of the ethanol-treated masks and, to a slightly lesser degree, the heat-treated masks. The VHP- and UV-treated masks retained comparable filtration performance to the control group after 2 rounds of decontamination and maintained acceptable performance after 3 rounds.
我们发现，VHP消毒既能在短时间内使新冠病毒失活，又能较好地保持N95呼吸器功能完整性（在实验室条件下），综合来看是最佳选择；紫外线在保持功能完整性方面的表现与VHP几乎一样好，但消毒速度要慢得多；70℃的干热与紫外线的消毒速度相似，也能让N95在一至两轮轮消毒后仍保持可接受的【acceptable】适合性，但不应超过三轮；与过往的结论(8)一致，酒精消毒会破坏N95功能完整性，并不推荐。
Our findings showed that VHP treatment had the best combination of rapid inactivation of SARS-CoV-2 virus and preservation of N95 respirator integrity under the experimental conditions (Figure, panel C). UV light killed the virus more slowly and preserved respirator function almost as well. Dry heat at 70ºC killed the virus with similar speed to UV and is likely to maintain acceptable fit scores for 1–2 rounds of decontamination but should not be used for 3 rounds. Consistent with earlier findings (8), ethanol decontamination reduced N95 integrity and is not recommended.
上述的所有消毒方法——尤其是紫外线和干热，在使用时都应有足够长的消毒时间来保证有效降低病毒浓度，具体需要的时间取决于初始的病毒污染程度。决策者可以用我们估计出的【病毒浓度】衰减曲线，结合实际估计的污染程度，来选择合适的处置时长（附录）。
All treatments, particularly UV light and dry heat, should be conducted for long enough to ensure sufficient reduction in virus concentration. The degree of required reduction depends upon the degree of initial virus contamination. Policymakers can use our estimated decay rates together with estimates of real-world contamination to choose appropriate treatment durations (Appendix).
我们的结果指出，在N95呼吸器短缺的时期，可以使用紫外线和VHP对其进行最多三次的消毒，或用干热进行一至两次的消毒。在此期间，请务必遵循国家制定的关于适合性试验、气密性检查和呼吸器复用的指南【guidelines】。我们建议每次消毒的时长要足，并在每次消毒后，利用现有的定性的适合性试验【QLFT】工具，确保呼吸器的功能完好。
Our results indicate that, in times of shortage, N95 respirators can be decontaminated and reused up to 3 times by using UV light and HPV and 1–2 times by using dry heat. Following nationally established guidelines for fit testing, seal check, and respirator reuse is critical (9,10). We recommend performing decontamination for sufficient time and ensuring proper function of the respirators after decontamination using readily available qualitative fit testing tools.
致谢（不翻了）
Acknowledgments
We thank Madison Hebner, Julia Port, Kimberly Meade-White, Irene Offei Owusu, Victoria Avanzato, and Lizzette Perez-Perez for excellent technical assistance.
This research was supported by the Intramural Research Program of the National Institute of Allergy and Infectious Diseases, National Institutes of Health. J.O.L.-S. and A.G. were supported by the Defense Advanced Research Projects Agency PREEMPT no. D18AC00031 and the UCLA AIDS Institute and Charity Treks, and J.O.L.-S. was supported by the US National Science Foundation (DEB-1557022), the Strategic Environmental Research and Development Program (RC‐2635) of the US Department of Defense.
关于作者（不翻了）
About the Author
Dr. Fischer is a member of the Virus Ecology Section at the Rocky Mountain Laboratories Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health. His research interests include the ecology of emerging viruses in their natural and spillover hosts, including SARS-CoV-2.
参考文献
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