key: cord-0977853-zv7k3k08 authors: Onofre, R.; Borges, R.; Demarco, G.; Dotto, L.; Schwendicke, F.; Demarco, F. title: Decontamination of N95 masks against coronavirus: a scoping review date: 2020-07-14 journal: nan DOI: 10.1101/2020.07.11.20151399 sha: dbd5b1f125696c8269f28d8e158b54f42079ac14 doc_id: 977853 cord_uid: zv7k3k08 Background: At present, it remains uncertain which method to decontaminate N95 is most suitable and should be recommended to healthcare professionals worldwide. Objectives: The aim of this scoping review was to map and compile the available evidence about the effectiveness of decontaminating N95 masks against coronavirus. Methods: We selected studies written in English assessing or discussing decontamination strategies of N95 masks against coronavirus. The search and study screening were performed in PubMed and SCOPUS by two independent researchers. A descriptive analysis was performed considering the study design of included studies. Results: We included nineteen studies. Eight articles were letter to the editors, five were in vitro studies, three were literature reviews, and three were classified as other study designs. The use of vaporized hydrogen peroxide and ultraviolet irradiation were the strategies most cited. However, there is a lack of evidence and consensus related to the best method of N95 masks decontamination. Conclusion: The evidence towards decontamination strategies of N95 masks against coronavirus remains scarce. Vaporized hydrogen peroxide and ultraviolet irradiation seem the current standard for N95 masks decontamination. The novel Coronavirus, known as SARS-Cov2, has produced a social disruption globally, with severe consequences for general health of the population. At the present moment, there are more than 11 million confirmed cases, with a cumulative number of deaths of over 500,000 according to World Health Organization (WHO) (updated data can be accessed in: https://www.worldometers.info/coronavirus/). Currently, vaccines are still under trial and there are no effective drugs for the treatment of this disease 1 . Indeed, most of the available evidence provided is that social distancing, wearing masks and eye protection are effective in the prevention of transmission 2 . Also, better hygiene (hand washing) and use of sanitizers are supported to detain spreading of the disease [3] [4] [5] . The use of masks has been recommended by WHO, and around the world governments have established face protection policies in public space 6 . The resulting increase in demand and a shortage in their availability in the market have led to price spikes for masks [7] [8] [9] [10] [11] . Health professionals are at high risk for infection with the new coronavirus, and a lack of adequate protective equipment during critical procedures in infected patients is increasing that risk considerably 12, 13 . In Brazil, for example, more nurses and nurses' assistants have died due to Covid-19 than anywhere else 14 and most of them have been infected during their work with infected patients. N95 masks are a type of respirator mask used as a facial protection specifically by healthcare providers 9, 15 . They have the capacity to filter over 95% of pollutant particles (>0.3 µm) in the air and have been suggested to be used to reduce the risk of Covid-19 spreading, too 16 . Due to their high costs and limited availability 8, 15 , different methods to decontaminate N95 masks 7, 15, [17] [18] [19] [20] [21] has been discussed to allow multiple usage. . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted July 14, 2020. . https://doi.org/10.1101/2020.07.11.20151399 doi: medRxiv preprint Decontamination methods can be classified into chemical or radiation treatment, dry heat or moist heat 9 . Such methods need to fulfill certain criteria: elimination of all pathogens; no damage to the facemask structure; the filter capacity of masks should stay the same; and no residue of the decontamination process should remain 9, 15 . At present, it remains uncertain which method to decontaminate N95 is most suitable and should be recommended to healthcare professionals worldwide. The aim of this scoping review was to map and compile the evidences about the effectiveness of different decontamination strategies of N95 masks against coronavirus. The protocol of this study is based on the framework proposed by Peters et al., 2015 22 and is available at the following link: https://osf.io/4t936/. The reporting of this scoping review was based on PRISMA Extension for Scoping Reviews 23 . We selected studies assessing different decontamination strategies of N95 masks against coronavirus or discussing decontamination strategies such as letters, editorials and literature review. No specifications towards the coronavirus organisms (surrogate or not) used to test decontamination or the decontamination strategies themselves were applied. The search was performed in two databases: Medline (PubMed) and Scopus; only articles written in English language were included. The search strategy was based on MeSH terms of PubMed and specific terms of Scopus and the last search was performed in May 2020. The following strategies were used: . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted July 14, 2020. . https://doi.org/10.1101/2020.07.11.20151399 doi: medRxiv preprint PubMed ((("Decontamination"[Mesh] OR "Decontamination" OR "Disinfection" OR "Ultraviolet-C" OR "peracetic acid")) AND ("Masks"[Mesh] OR "Masks" OR "Respiratory Protective Devices"[Mesh] OR "Respiratory Protective Devices" OR "Device, Respiratory Protective" OR "Devices, Respiratory Protective" OR "Protective Device, Respiratory" OR "Protective Devices, Respiratory" OR "Respiratory Protective Device" OR "Respirators, Industrial" OR "Industrial Respirators" OR "Industrial Respirator" OR "Respirator, Industrial" OR "Respirators, Air-Purifying" OR "Air-Purifying Respirator" OR "Air-Purifying Respirators" OR "Respirator, Air-Purifying" OR "Respirators, Air Purifying" OR "N95")) AND ("SARS-CoV-2" OR "Coronavirus" OR "COVID-19" OR "Coronaviruses") SCOPUS "Decontamination" OR "Disinfection" OR "Ultraviolet-C" OR "peracetic acid" AND "Masks" OR "Respiratory Protective Devices" OR "Device, Respiratory Protective" OR "Devices, Respiratory Protective" OR "Protective Device, Respiratory" OR "Protective Devices, Respiratory" OR "Respiratory Protective Device" OR "Respirators, Industrial" OR "Industrial Respirators" OR "Industrial Respirator" OR "Respirator, Industrial" OR "Respirators, Air-Purifying" OR "Air-Purifying Respirator" OR "Air-Purifying Respirators" OR "Respirator, Air-Purifying" OR "Respirators, Air Purifying" OR "N95" AND "SARS-CoV-2" OR "Coronavirus" OR "COVID-19" OR "Coronaviruses" The search was undertaken using EndNote (EndNote X9, Thomson Reuters, New York, US). Two researches independently identified relevant records by analyzing titles and abstracts for relevance according to the eligibility criteria. Retrieved records were classified as include, exclude, or uncertain. The full-text articles of the included and . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted July 14, 2020. . https://doi.org/10.1101/2020.07.11.20151399 doi: medRxiv preprint uncertain records were selected for further eligibility screening by the same two reviewers, again independently. Discrepancies in screening of titles/abstracts and full text articles were resolved through a discussion. In case of disagreement, the opinion of a third reviewer was garnered. We created a form using Excel (Microsoft, Redmond, Washington, US), which was pilot tested by three reviewers to reach a consensus on what data to collect and how. Then, two reviewers extracted the data independently, this was reviewed by a third reviewer. The following data were collected: study design; study objective, decontamination regimens tested, organisms studied, method of evaluation and main findings. For studies only discussing (and not reporting on) decontamination strategies, the following data were collected: study design, strategies discussed and main findings. A descriptive analysis was performed considering the study design and decontamination regimens tested or discussed. The literature search yielded 178 titles and abstracts (Fig. 1) . Nineteen studies 7, 8, 15, [17] [18] [19] [20] [21] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] fulfilled the eligibility criteria from which the data were extracted. Reasons for exclusion are listed in the Supplemental Material. 7, 19, 21, 25, 31 , three were literature reviews 17, 24, 27 , and three were . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted July 14, 2020. . https://doi.org/10.1101/2020.07.11.20151399 doi: medRxiv preprint classified as other study designs 30, 32, 34 . Considering only the eight letters to the editors, three letters discussed results of in vitro studies 8, 15, 18 . Related to decontamination regimens tested or discussed, the use of vaporized hydrogen peroxide and ultraviolet irradiation were the regimens most cited. The use of vaporized hydrogen peroxide was cited in four letters 18, 20, 28, 33 , three in vitro studies 7, 25, 31 , two reviews 17, 24 and two other study designs 30, 32 . The use of ultraviolet irradiation vaporized hydrogen peroxide was cited in five letters 9, 20, 26, 28, 29 , two in vitro studies 7, 21 , two reviews 17, 24 and two other study designs 30, 32 . Three studies reported the process for N95 decontamination with vaporized Grossman et al. 2020 described the decontamination using vaporized hydroperoxide employed by Washington University (US). They demonstrated that the entire process requires less than 24 hours and showed that it is important to create a workflow to achieve an effective decontamination considering pre-processing steps, decontamination process and, post-processing steps 25 . Further studies evaluated that strategy combined with others or discussed its availability and feasibility. Cadnum et al. 2020 performed an in vitro study and compared the use of a high-level decontamination cabinet that generates aerosolized . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted July 14, 2020. . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted July 14, 2020. Garcia-Godoy et al. 2020 discussed that the Ultraviolet germicidal irradiation seems to be one of the most promising method for N95 decontamination 24 . Narla et al. 2020 highlighted that is necessary at least 1 J/cm2 to all surfaces to ensure N95 decontamination. However, the authors emphasized that Ultraviolet decontamination has limitations, mainly as each type of mask needs a specific dosage of irradiation to be reliably effective 29 . Carillo et al. 2020 indicated that immediate use steam sterilization is an applicable decontamination method 15 This is the first study to map the evidence about the effectiveness of decontamination strategies of N95 masks against coronavirus. Our results demonstrate that there is a lack of evidence and consensus related to the best method of N95 masks decontamination. However, the use of vaporized hydrogen peroxide and ultraviolet . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted July 14, 2020. . https://doi.org/10.1101/2020.07.11.20151399 doi: medRxiv preprint irradiation were the regimens most cited and seem to be the most promising methods for N95 masks decontamination. Hydrogen peroxide vapor decontamination is a common method used in different fields and facilities, including scientific, pharmaceutical, and medical ones. The method has low toxicity and uses the catalytic reduction of peroxide to oxygen and water 35 . However, it needs a specific room and equipment to achieve an effective decontamination and, hence, is rather expensive. Ultraviolet irradiation is a method of decontamination using Ultraviolet light to inactivate microorganisms through DNA damage and jeopardizing cell functions 36 . The use of this decontamination method has limitations due different mask needing different irradiation dosages; high dosage in turn could result in high toxicity and structural damage of the mask. Moreover, it also needs specific equipment, limiting its availability. Ideally, any decontamination method should eliminate all pathogens; maintain mask integrity and filter capacity; at low toxicity and costs. Until a method does not fulfill these criteria, the extended use of masks seems to be a good and low-cost approach to overcome the discussed limitations in availability. Current recommendations consider mask wearing periods between 4 and 40 hours 28 . Notably, additional protection such as use of face shield and strict adherence to hand hygiene practices are needed, especially if extending mask wearing periods 37 . Outcomes such as mechanical integrity and performance of N95 masks should be observed when assessing decontamination strategies of N95 masks, as decontamination may come at a price; decontaminated but not effective masks are not useful or even dangerous. Ozog et al., 2020 indicated that a fit testing must be performed after decontamination and if a decontamination is achieved but the masks lost their integrity, further usage should be stopped 20 . Hence, both integrity and . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted July 14, 2020. . performance should be prioritized when implementing decontamination strategies, while not all included studies concomitantly tested decontamination and subsequent performance of the mask. Our study presents some limitations. First, because this was a scoping review, we did not conduct a risk of bias/quality assessment of the included studies. Second, we included only studies in English. Third, the included studies present different designs and protocols, making it difficult to compare the results specially because many brands of N95 are available on the market, different regimens were tested and individual scenarios of wearers (such as, influence of as cosmetics or sunscreens use for Ultraviolet decontamination) are difficult to test. Finally, we included article discussing decontamination methods based on opinions over evidences making it difficult better conclusions and recommendations. Considering that the global pandemic accelerates its spread at present, and taking into account the shortage of protective equipment, especially for healthcare workers, more investigations for safely decontaminating N95 masks are needed. Also, the availability and cost-effectiveness of decontamination should be considered by future studies. The evidence towards decontamination strategies of N95 masks against coronavirus remains scarce. Vaporized hydrogen peroxide and ultraviolet irradiation seem the current standard for N95 masks decontamination. . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted July 14, 2020. . https://doi.org/10.1101/2020.07.11.20151399 doi: medRxiv preprint The authors deny any conflicts of interest related to this study. . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted July 14, 2020. . Hamzavi . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted July 14, 2020. . . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted July 14, 2020. . However, efficacy varied with different respirator types and with different locations on the respirator. A high-level disinfection cabinet using submicron droplets of aerosolized peracetic acid and hydrogen peroxide was substantially more effective for decontamination of N95 respirators and with 3 consecutive cycles or a single extended cycle achieved >6-log10 reductions meeting criteria for disinfection." . It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted July 14, 2020. The study shows that overall, strategies involving the use of UVGI, ethylene oxide, dry oven heating and hydrogen peroxide may be most promising for preservation of mask function and integrity. Decontamination with UVGI, moist heat incubation and microwavegenerated steam does not appear to significantly affect N95 respirator fit or comfort. Until application of these methods has been adequately investigated in the hospital setting, their safety and effectiveness in the particular context of the SARS-CoV-2 outbreak is unknown." . It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted July 14, 2020. "The study shows that a reproducible and scalable process for implementing N95 respirator disinfection within a large academic hospital and healthcare system is achievable through multidisciplinary collaboration and rapid adaptation in the setting of the COVID-19 pandemic and critical N95 respirator shortages." Hamzavi et al., 2020 Letter Letter proposing a possible repurposing of phototherapy devices, including these UVB units, to serve as a platform for UVC germicidal disinfection. Ultraviolet germicidal irradiation (UVGI) SARS-CoV --"UVGI and repurposing phototherapy devices could be the best practical solution at this time." . It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted July 14, 2020. . https://doi.org/10.1101/2020.07.11.20151399 doi: medRxiv preprint Published data were reviewed to find out which temperature and exposure time is necessary for inactivation of coronaviruses. Thermal disinfection (various temperatures) SARS-CoV --"Overall a thermal disinfection at 60°C for 30 min, 65°C for 15 min and 80°C for 1 min was effective to strongly reduce coronavirus infectivity. Data do not allow to evaluate if the function of a face mask remains unchanged after heat treatment. If thermal disinfection is used for the re-use of masks all institutions should evaluate the effect on their own masks in use, as different brands of masks and different specifications (e.g. with or without cellulose) will react individually towards a combination of time and heat. Easy tests to do are "fitting" and "water-resistance". In addition, the numbers of re-uses should be traced (mark at the side of mask per cycle) and its effects examined." Kobayashi et al., 2020 Letter showing an overview of national regulatory authority recommendations. Dry heat in a drying cabinet at 65-70°C (Germany); vaporous hydrogen peroxide (Netherlands, Europe, and the United States); ultraviolet germicidal irradiation and moist heat (Europe and the United States) ---"The Ministry of Labor and Social Affairs of Germany described the recommended decontamination method for N95 respirators in detail (ie, dry heat at 65-70°C in a drying cabinet for 30 minutes). On the other hand, up to 60% of the screened countries did not report any recommendations for extended use or reuse or decontamination of N95 respirators." . It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted July 14, 2020. "The results of the study demonstrate that steam treatment using a rice cookersteamer is effective for decontamination of face masks and N95 respirators. Investigations of moist heat are also needed as 20 minutes of exposure to moist heat at 65°C has been reported to be effective with minimal adverse effects on respirator performance." Ma et al., 2020 In vitro The study verified a simple decontamination measure suitable to most people for reuse of MMs and N95Ms. Avian coronavirus of infectious bronchitis virus H120 Vaccine strain of avian infectious bronchitis virus H120 RT-PCR "The study observes that if a mask will be reused, it should be doffed without touching its surface, and the doffed mask should be put directly into a plastic bag or stainless-steel box for steam and avoiding contamination of the surface of other items. They also presume that the masks can be used for up to seven or ten days, if they keep clean and fitted, and have not been damaged by other factors. Therefore, this study is valuable for solving the great shortage of masks in many countries for fighting the COVID-19 pandemic. It can also minimize unnecessary waste and protect the environment for discarding reusable masks." Narla et al. The study states that it should also be emphasized that there are significant limitations to UVC decontamination methods due to the variety of respirators used in healthcare facilities. Consequently, this process should only be considered as a risk mitigation effort during severe shortage of N95 respirators but is one of the most effective and best studied options available to front-line . It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted July 14, 2020. The study discussed about fit-testing performance collected for the different respirator models treated with UVGI. "The data of this study strongly indicates that to protect the safety of the N95 respirator user, fit-testing after decontamination must be done each time a new model is introduced to a healthcare system. This has significant safety implications as varied decontamination methods are being used by different institutions." . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted July 14, 2020. Article discussed concern regarding the shortage in supply chain of critical onetime-use personal and protective equipment. Vaporised hydrogen peroxide, UV irradiation and High-level liquid disinfection (Actichlor+), The article observes that the best evidence suggests that preferred candidate methods for meeting this gap appears to be use of vaporised hydrogen peroxide (VHP) and UV irradiation technologies." . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted July 14, 2020. The study talks about a quality assurance (QA) step, after complete aeration, to ensure both qualitative and quantitative degradation has not occurred, ensuring that there was no physical or performance degradation. Also, a standardized quantitative fit testing was preformed to ensure the integrity of the respirators is maintained over many decontamination cycles. In addition, we validated the efficacy of the decontamination process by using 9 individual 6-log biological indicators (Geobacillus stearothermophilus spores). "Using hydrogen peroxide vapor is a proven method of decontamination. Authors believe that decontamination of N95 respirators with hydrogen peroxide vapor is one such solution that affords us better ability to protect our health care workers as we continue to tackle this monumental issue." . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted July 14, 2020. "The results demonstrated that the size range of the droplets was 0.5 to 15 m and that the majority of the droplet particles were between 0.74 and 3.5 m in diameter. Treatment with sodium hypochlorite (bleach) was an efficient chemical decontamination method for MS2 virus loaded onto FFRs. Treatment with low sodium hypochlorite doses (2.75 to 5.50mg/liter) resulted in approximately 3to 4-log reductions in the levels of MS2 coliphage, while treatment with higher sodium hypochlorite doses (8.25 mg/liter) resulted in no detectable MS2 virus. UV irradiation was also demonstrated to be an efficient physical decontamination treatment for MS2 virus. Treatment with low UV irradiation doses (4.32 to 5.76 J/cm2) resulted in 3.00-to 3.16-log reductions in the levels of MS2 coliphage, while treatment with higher UV irradiation doses (7.20 J/cm2) resulted in no detectable MS2 virus." Findings based on the article reporting . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted July 14, 2020. CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted July 14, 2020. . Writing -Review & Editing REFERENCES 1. 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CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted July 14, 2020. . https://doi.org/10.1101/2020.07.11.20151399 doi: medRxiv preprint