• Thomas Sean Lendvay, James Chen, Brian H Harcourt, Florine E M Scholte, Ying Ling Lin, F Selcen Kilinc-Balci, Molly M Lamb, Kamonthip Homdayjanakul, Yi Cui, Amy Price, Belinda Heyne, Jaya Sahni, Kareem B Kabra, Yi-Chan Lin, David Evans, Christopher N Mores, Ken Page, Larry F Chu, Eric Haubruge, Etienne Thiry, Louisa F Ludwig-Begall, Constance Wielick, Tanner Clark, Thor Wagner, Emily Timm, Thomas Gallagher, Peter Faris, Nicolas Macia, Cyrus J Mackie, Sarah M Simmons, Susan Reader, Rebecca Malott, Karen Hope, Jan M Davies, Sarah R Tritsch, Lorène Dams, Hans Nauwynck, Jean-Francois Willaert, Simon De Jaeger, Lei Liao, Mervin Zhao, Jan Laperre, Olivier Jolois, Sarah J Smit, Alpa N Patel, Mark Mayo, Rod Parker, Vanessa Molloy-Simard, Jean-Luc Lemyre, Steven Chu, John M Conly, and May C Chu.
• Department of Urology, University of Washington School of Medicine, Seattle Children's Hospital, Seattle, Washington, United States.
• Infect Control Hosp Epidemiol. 2021 May 21: 1-10.

ObjectiveThe 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.DesignThe 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.MethodsMBL 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+O3) decontamination method.ResultsOverall, 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+O3.ConclusionsMBL 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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