Disinfection of SARS-CoV-2 using UVC reveals wavelength sensitivity contributes towards rapid virucidal activity

Abstract SARS-CoV-2 is a pathogen that can be disinfected using UVC. For effective inactivation strategies, design and implementation of UVC disinfection, knowledge of wavelength sensitivity, and disinfection rate of the relevant pathogen are required. This study aimed to determine the inactivation profile of SARS-CoV-2 using UVC irradiation with different wavelengths, in addition to validating surrogate models for SARS-CoV-2. Specifically, the study determined dosage, inactivation levels, and wavelength sensitivity of SARS-CoV-2. Assessment of SARS-CoV-2 (Strain USA/WA1-2020) inactivation at peak wavelength of 259, 268, 270, 275 and 280 nm was performed using plaque assay method. The UVC dose of 3.1 mJ/cm2 using 259 and 268 nm arrays yielded LRV2.32 and LRV2.44 respectively. With a dose of 5mJ/cm2, arrays of peak wavelengths at 259 and 268 nm obtained similar inactivation (LRV2.97 and LRV 2.80 respectively). The remaining arrays of longer wavelength, 270, 275 and 280 nm, demonstrated lower performances (LRV2.0 or less) with 5mJ/cm2. Additional study with the 268 nm array revealed that a dose of 6.25 mJ/cm2 (with 5 seconds or irradiation) is enough to obtain LRV3. These results determine that 259 and 268 nm are the most efficient wavelengths compared to longer UVC wavelengths, allowing the calculation of disinfection systems efficacy, and providing a benchmark for surrogates.