Personal Protective Equipment (PPE) is required to safely work with biological agents of bacterial (i.e. Mycobacterium tuberculosis) or viral origin (Ebola and SARS). COVID-19 pandemic especially has created unforeseen public health challenges including a global shortage of PPE needed for the safety of health care workers (HCWs). Although sufficient stocks of PPE are currently available, their critical shortage may develop soon due to increase in demand and depletion of existing supply lines. To empower our HCWs and ensure their continued protection, proactive measures are urgently required to develop procedures to safely decontaminate the PPEs to allow their “selective reuse” during contingency situations. Herein, we have successfully developed a decontamination method based on vaporized hydrogen peroxide (VHP). We have used a range of concentration of hydrogen peroxide to disinfect PPE (coveralls, face-shields, and N-95 masks). To ensure a proper disinfection, we have evaluated three biological indicators namely Escherichia coli, Mycobacterium smegmatis and spores of Bacillus stearothermophilus, considered as the gold standard for disinfection processes. We next evaluated the impact of repeated VHP treatment on physical features, permeability, and fabric integrity of coveralls and N-95 masks. Next, we performed Scanning Electron Microscopy (SEM) to evaluate microscopic changes in fiber thickness of N-95 masks, melt blown layer or coverall body suits. Considering the fact that any disinfection procedure should be able to meet local requirements, our study included various regionally procured N-95 masks and coveralls available at our institute All India Institute of Medical Sciences (AIIMS), New Delhi, India. Lastly, the practical utility of VHP method developed herein was ascertained by operationalizing a dedicated research facility disinfecting used PPE during COVID-19. Our prototype studies show that a single VHP cycle (7–8% Hydrogen peroxide) could disinfect PPE and PPE housing room of about 1200 cubic feet (length10 ft × breadth 10 ft × height 12 ft) in less than 10 min, as noted by a complete loss of B. stearothermophilus spore revival. The results are consistent and reproducible as tested in over 10 cycles in our settings. Further, repeated VHP treatment did not result in any physical tear, deformity or other appreciable change in the coverall and N-95 masks. Our permeation tests evaluating droplet penetration did not reveal any change in permeability post-VHP treatments. Also, SEM analysis indeed revealed no significant change in fiber thickness or damage to fibers of coveralls or melt blown layer of N-95 masks essential for filtration. There was no change in user comfort and experience following VHP treatment of PPE. Based on results of these studies, and parameters developed and optimized, an institutional research facility to disinfect COVID-19 PPE is successfully established and operationalized with more than 80% recovery rate for used PPE post-disinfection. Our study, therefore, successfully establishes the utility of VHP to effectively disinfect PPE for a possible reuse as per the requirements. VHP treatment did not damage coveralls, cause physical deformity and also did not alter fabric architecture of melt blown layer. We observed that disinfection process was successful consistently and therefore believe that the VHP-based decontamination model will have a universal applicability and utility. This process can be easily and economically scaled up and can be instrumental in easing global PPE shortages in any biosafety facility or in health care settings during pandemic situation such as COVID-19.

中文翻译：

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开发一种高效低成本的基于汽化过氧化氢的方法，用于对个人防护设备进行消毒，以便在大流行期间对其进行选择性重复使用。

个人防护装备 (PPE) 需要安全地处理细菌（即结核分枝杆菌）或病毒来源（埃博拉和 SARS）的生物制剂。COVID-19 大流行尤其带来了不可预见的公共卫生挑战，包括全球医护人员 (HCW) 安全所需的个人防护装备短缺。尽管目前有足够的 PPE 库存，但由于需求增加和现有供应线耗尽，它们可能很快就会严重短缺。为了增强我们的医护人员的能力并确保他们的持续保护，迫切需要采取积极措施来制定安全净化 PPE 的程序，以便在紧急情况下“选择性重复使用”。在此，我们成功开发了一种基于汽化过氧化氢 (VHP) 的去污方法。我们使用了一系列浓度的过氧化氢来对 PPE（工作服、面罩和 N-95 口罩）进行消毒。为确保正确消毒，我们评估了三种生物指标，即大肠杆菌、耻垢分枝杆菌和嗜热脂肪芽孢杆菌孢子，这被认为是消毒过程的金标准。接下来，我们评估了重复 VHP 处理对工作服和 N-95 口罩的物理特性、渗透性和织物完整性的影响。接下来，我们进行了扫描电子显微镜 (SEM) 以评估 N-95 口罩、熔喷层或连体服的纤维厚度的微观变化。考虑到任何消毒程序都应该能够满足当地的要求，我们的研究包括在我们位于印度新德里的全印度医学科学研究所 (AIIMS) 提供的各种区域采购的 N-95 口罩和工作服。最后，通过在 COVID-19 期间对使用过的 PPE 进行消毒的专用研究设施的运行，确定了本文开发的 VHP 方法的实用性。我们的原型研究表明，单个 VHP 循环（7-8% 的过氧化氢）可以在不到 10 分钟的时间内对 PPE 和约 1200 立方英尺（长 10 英尺×宽 10 英尺×高 12 英尺）的 PPE 和 PPE 住房进行消毒，如B. stearothermophilus 孢子复活的完全丧失。在我们的设置中经过 10 多个周期的测试，结果是一致且可重现的。此外，重复的 VHP 处理不会导致工作服和 N-95 面罩出现任何物理撕裂、变形或其他明显变化。我们评估液滴渗透的渗透测试未显示 VHP 处理后渗透性有任何变化。此外，SEM 分析确实显示纤维厚度没有显着变化，工作服纤维或过滤必不可少的 N-95 口罩的熔喷层也没有损坏。对 PPE 进行 VHP 处理后，用户的舒适度和体验没有变化。根据这些研究的结果，以及开发和优化的参数，成功建立并运行了一个对 COVID-19 PPE 进行消毒的机构研究设施，消毒后用过的 PPE 的回收率超过 80%。因此，我们的研究成功地确定了 VHP 的实用性，可以根据要求有效地对 PPE 进行消毒，以便可能重复使用。VHP 处理不会损坏工作服，导致物理变形，也没有改变熔喷层的织物结构。我们观察到消毒过程始终如一地成功，因此相信基于 VHP 的去污模型将具有普遍的适用性和实用性。这一过程可以轻松、经济地扩大规模，并有助于缓解任何生物安全设施或医疗保健机构在 COVID-19 等大流行病期间的全球 PPE 短缺。