Addressing personal protective equipment (PPE) decontamination: Methylene blue and light inactivates severe acute respiratory coronavirus virus 2 (SARS-CoV-2) on N95 respirators and medical masks with maintenance of integrity and fit
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Abstract
Objective:
The coronavirus disease 2019 (COVID-19) pandemic has resulted in shortages of personal protective equipment (PPE), underscoring the urgent need for simple, efficient, and inexpensive methods to decontaminate masks and respirators exposed to severe acute respiratory coronavirus virus 2 (SARS-CoV-2). We hypothesized that methylene blue (MB) photochemical treatment, which has various clinical applications, could decontaminate PPE contaminated with coronavirus.
Design:
The 2 arms of the study included (1) PPE inoculation with coronaviruses followed by MB with light (MBL) decontamination treatment and (2) PPE treatment with MBL for 5 cycles of decontamination to determine maintenance of PPE performance.
Methods:
MBL treatment was used to inactivate coronaviruses on 3 N95 filtering facepiece respirator (FFR) and 2 medical mask models. We inoculated FFR and medical mask materials with 3 coronaviruses, including SARS-CoV-2, and we treated them with 10 µM MB and exposed them to 50,000 lux of white light or 12,500 lux of red light for 30 minutes. In parallel, integrity was assessed after 5 cycles of decontamination using multiple US and international test methods, and the process was compared with the FDA-authorized vaporized hydrogen peroxide plus ozone (VHP+O 3 ) decontamination method.
Results:
Overall, MBL robustly and consistently inactivated all 3 coronaviruses with 99.8% to >99.9% virus inactivation across all FFRs and medical masks tested. FFR and medical mask integrity was maintained after 5 cycles of MBL treatment, whereas 1 FFR model failed after 5 cycles of VHP+O 3 .
Conclusions:
MBL treatment decontaminated respirators and masks by inactivating 3 tested coronaviruses without compromising integrity through 5 cycles of decontamination. MBL decontamination is effective, is low cost, and does not require specialized equipment, making it applicable in low- to high-resource settings.
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SciScore for 10.1101/2020.12.11.20236919: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement IRB: A SARS-CoV-2 clinical saliva specimen with a titer of 1.1 × 105 PFU/ml was obtained with the University of Calgary Conjoint Health Research Ethics Board approval (ID# REB20-0444). Randomization not detected. Blinding not detected. Power Analysis not detected. Sex as a biological variable not detected. Cell Line Authentication not detected. Table 2: Resources
Experimental Models: Cell Lines Sentences Resources Vero CCL-81 cells were purchased from ATCC and cultured in DMEM supplemented with 10% FBS, 1% GlutaMAX, 1% Pen/Strep, and 0.1% Amphotericin B. Alternatively, Vero CCL-81 cells were cultured in MEM supplemented with 2 mM L-glutamine, 1 mM Sodium Pyruvate, 1x NEAA, … SciScore for 10.1101/2020.12.11.20236919: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement IRB: A SARS-CoV-2 clinical saliva specimen with a titer of 1.1 × 105 PFU/ml was obtained with the University of Calgary Conjoint Health Research Ethics Board approval (ID# REB20-0444). Randomization not detected. Blinding not detected. Power Analysis not detected. Sex as a biological variable not detected. Cell Line Authentication not detected. Table 2: Resources
Experimental Models: Cell Lines Sentences Resources Vero CCL-81 cells were purchased from ATCC and cultured in DMEM supplemented with 10% FBS, 1% GlutaMAX, 1% Pen/Strep, and 0.1% Amphotericin B. Alternatively, Vero CCL-81 cells were cultured in MEM supplemented with 2 mM L-glutamine, 1 mM Sodium Pyruvate, 1x NEAA, 1% Pen/Strep, 0.1 CCL-81suggested: NoneVero CCL-81suggested: NoneVero E6 cells (ATCC) were cultured in DMEM supplemented with 10% FBS and 1% GlutaMAX. Vero E6suggested: NoneSoftware and Algorithms Sentences Resources Model 8130, TSI, Inc.) and according to the National Personal Protective Technology Laboratory (NPPTL National Personal Protective Technology Laboratorysuggested: NoneEC50s were calculated using GraphPad Prism 8. GraphPad Prismsuggested: (GraphPad Prism, RRID:SCR_002798)Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).
Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:There were limitations to this study. We only tested 3 types of FFRs, yet there are approximately 500 N95 FFR models approved by NIOSH and many medical masks around the world. Each FFR, MM, or CM model has distinct filter/strap/ear loop/tie materials and design characteristics (e.g., surface area, dead space, nose padding). The differences in materials and design characteristics among all available FFR/MM/CM models result in variable outcomes for decontamination efficacy and effect of decontamination on FFR performance. CDC recommends that a decontamination method’s effectiveness be evaluated for specific FFR models in collaboration with the manufacturer, and if needed, a third-party laboratory (21). Another limitation within our study was that our primary inactivation studies were performed with direct application of a fixed quantity of MB onto coupons and only two of our experiments tested the spraying of MB onto a whole mask or the soaking of PPE material into a solution of MB. We attempted to normalize the volume of MB applied to the coupons to the amount of per square surface area. For example, if 7-8 mL of MB solution was sprayed onto an intact mask (4 sprays on outer and 2 sprays on inner surface), based on the surface area of a 3M N95 1860 respirator (RM), this would result in 10-30 ul of MB for the each 1 cm2 coupon. In our clinical specimen experiment, we demonstrated SARS-CoV-2 inactivation with MBL. Obtaining whole masks worn by healthcare personnel who cared for ...
Results from TrialIdentifier: No clinical trial numbers were referenced.
Results from Barzooka: We found bar graphs of continuous data. We recommend replacing bar graphs with more informative graphics, as many different datasets can lead to the same bar graph. The actual data may suggest different conclusions from the summary statistics. For more information, please see Weissgerber et al (2015).
Results from JetFighter: We did not find any issues relating to colormaps.
Results from rtransparent:- Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
- Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
- No protocol registration statement was detected.
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