key: cord-0943777-wn85ilbh authors: Dwivedi, Varun; Park, Jun-Gyu; Grenon, Stephen; Medendorp, Nicholas; Hallam, Cory; Torrelles, Jordi B.; Martinez-Sobrido, Luis; Kulkarni, Viraj title: Rapid and Efficient Inactivation of SARS-CoV-2 from Surfaces using UVC Light Emitting Diode Device date: 2021-04-21 journal: bioRxiv DOI: 10.1101/2021.04.20.440654 sha: 45b2e29ea1c4dcf366bc2875fae7f396c7ed5529 doc_id: 943777 cord_uid: wn85ilbh Efforts are underway to develop countermeasures to prevent the environmental spread of COVID-19 pandemic caused by SARS-CoV-2. Physical decontamination methods like Ultraviolet radiation has shown to be promising. Here, we describe a novel device emitting ultraviolet C radiation (UVC), called NuvaWave, to rapidly and efficiently inactivate SARS-CoV-2. SARS-CoV-2 was dried on a chambered glass slides and introduced in a NuvaWave robotic testing unit. The robot simulated waving NuvaWave over the virus at a pre-determined UVC radiation dose of 1, 2, 4 and 8 seconds. Post-UVC exposure, virus was recovered and titered by plaque assay in Vero E6 cells. We observed that relative control (no UVC exposure), exposure of the virus to UVC for one or two seconds resulted in a >2.9 and 3.8 log10 reduction in viral titers, respectively. Exposure of the virus to UVC for four or eight seconds resulted in a reduction of greater than 4.7-log10 reduction in viral titers. The NuvaWave device inactivates SARS-CoV-2 on surfaces to below the limit of detection within one to four seconds of UVC irradiation. This device can be deployed to rapidly disinfect surfaces from SARS-CoV-2, and to assist in mitigating its spread in a variety of settings. The coronavirus disease 2019 pandemic caused by severe acute respiratory 48 syndrome-coronavirus-2 (SARS-CoV-2) has caused a major public health and economic 49 crisis. 1 It is reported that SARS-CoV-2 originated in Wuhan city, China's Hebei province, Person-to-person transmission of the SARS-CoV-2 is primarily via aerosols expelled by 62 an infectious person and inhales via a susceptible person. 9, 10 SARS-CoV-2 transmission 63 through contaminated surfaces has also been reported. 10 (Fig. 1a) . It is intended to disinfect surfaces with non-ionizing UVC radiation by 105 waving the device 1 to 3.5 inches over the surface. The patent-pending technology 106 ensures adequate germicidal dosage is delivered over the entire 4 inches x 4 inches 107 exposure area and at distances between 1 and 3.5 inches. The UVC light source is instant 108 on/off and is controlled with a simple trigger mechanism. The system utilizes an external 109 battery pack rated for up to 3 hours of use and incorporates a computer monitoring system 110 which ensures consistent performance over time. To test the efficacy of this device the 111 same light engine as the NuvaWave Handheld and packaged in a computer controlled 112 robotic test fixture (Fig. 1b) . The robotic test fixture was engineered to hold a chambered 113 glass slide on to which virus sample was placed. Exposure of SARS-CoV-2 to UVC -Fifty microliters containing 3.5 x 10 6 PFU/ml SARS-115 CoV-2 viral stock was placed on one well of a 4-well chambered glass slide (Nunc, Sigma) 116 (Fig 2) . Five slides were used for 5 different exposure conditions: no exposure, 1, 2, 4 117 and 8 seconds UVC transverse exposure times. The virus was allowed to dry in a 118 biosafety cabinet in a BSL3 laboratory for 1 hour at room temperature (RT). After drying, 119 the slide was placed into the NuvaWave Robotic Test Fixture and exposed to UVC light 120 radiation for the predetermined exposure conditions. Immediately after exposure the virus 121 was reconstituted in 50 ml of DMEM and 10-fold serial dilutions were performed to 122 measure viral titers. NuvaWave handheld device is shown in Fig. 1A . Testing was performed using the same 152 light engine as the NuvaWave Handheld and packaged in a computer controlled robotic 153 test fixture (Fig. 1B) . The light engine was mounted 2 inches from the sample while the 154 sample and a sensor were moved on a stage at a constant speed under the light source. In this study, we mimic the NuvaWave operator waving the device in a single pass over 193 a surface. To facilitate the study, a robotic testing system was created (Fig. 1B) : Schematic representation of the workflow. SARS-CoV-2 was placed on the chambered glass slide, dried for 1 hour at room temperature, and then exposed to UVC light radiation using the NuvaWave device for 1, 2, 4 and 8 seconds. No UVC light exposure was used as control. After UVC light exposure, virus was recovered, serial diluted and used to assess viable virus in Vero E6 cells by the plaque assay. seconds. This tester was built with a polycarbonate surrounding, so the operator was not 205 exposed to any stray UV light (Fig. 1B) . This device is identical to the commercially intervention thus minimizing any human error in the UVC exposure methodology. UVC 219 dosage (Joules/cm 2 ) were recorded after each exposure (Fig. 3) . The dosage of UVC (Fig. 3) . For our unexposed controls, we report a viral recovery of 5.7 log10 plaque forming units 241 (mean value of n=5 in duplicate) per ml (PFU/ml) (Fig. 3 and Table 1 ). UVC light exposed 242 virus for one or two seconds resulted in >2.9 log10 and >3.8 log10 reductions in viral titers, 243 respectively, when compared to the unexposed control ( Fig. 3 and Table 1 ). Exposure of 244 the virus to UVC for four or eight seconds resulted in both cases in a reduction of over 245 Note: <1-log10 = below the limit of detection; *<1-log10 was considered as 1-log10 for calculation purposes the detection limit of the assay (>4.7 log10 reduction) in viral titers relative to our 246 unexposed control ( Fig. 3 and Table 1 ). 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