Quantitative evaluation of SARS-CoV-2 inactivation using a deep ultraviolet light-emitting diode

Abstract

Inactivation technology for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is certainly a critical measure to mitigate the spread of coronavirus disease 2019 (COVID-19). A deep ultraviolet light-emitting diode (DUV-LED) would be a promising candidate to inactivate SARS-CoV-2, based on the well-known antiviral effects of DUV on microorganisms and viruses. However, due to variations in the inactivation effects across different viruses, quantitative evaluations of the inactivation profile of SARS-CoV-2 by DUV-LED irradiation need to be performed. In the present study, we quantify the irradiation dose of DUV-LED necessary to inactivate SARS-CoV-2. For this purpose, we determined the culture media suitable for the irradiation of SARS-CoV-2 and optimized the irradiation apparatus using commercially available DUV-LEDs that operate at a center wavelength of 265, 280, or 300 nm. Under these conditions, we successfully analyzed the relationship between SARS-CoV-2 infectivity and the irradiation dose of the DUV-LEDs at each wavelength without irrelevant biological effects. In conclusion, total doses of 1.8 mJ/cm2 for 265 nm, 3.0 mJ/cm2 for 280 nm, and 23 mJ/cm2 for 300 nm are required to inactivate 99.9% of SARS-CoV-2. Our results provide quantitative antiviral effects of DUV irradiation on SARS-CoV-2, serving as basic knowledge of inactivation technologies against SARS-CoV-2.

A systematic scoping review of ultraviolet C (UVC) light systems for SARS-CoV-2 inactivation

“…As a result, 315 publications were screened and 297 were excluded after reading the title and/or abstract. Eighteen records were assessed for eligibility and 13 were included in this review ( 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ). Five studies were excluded because they did not meet our inclusion criteria, i.e., two studies did not provide enough information about the UVC system ( 23 , 24 ), one did not present quantitative data for SARS-CoV-2 inactivation ( 25 ), one reported data using SARS-CoV-2 surrogates ( 26 ) and one used UVA-based technology ( 27 ) ( Figure 2 ).…”

“…UVC was better than ozone except for wood (O 3 : 93.3% inactivation) ( 13 ) Investigating the susceptibility of SARS-CoV-2 to combined or separated UVA and UVC UVC was more effective: 99.999% (5-log) ( 14 ) Validating inactivation protocols from differentiated AECs cultures infected with live SARS-CoV-2 > 99.99% (4-log) ( 15 ) Investigating UVC on SARS-CoV-2 inactivation 99.7% (2.51-log) ( 16 ) Investigating continuous and intermittent UVC on SARS-CoV-2 inactivation > 99.99% (> 4-log). No difference between continuous and intermittent light ( 17 ) Evaluating the antiviral efficacy of deep UV-LED on SARS-CoV-2 99.9% (3-log) ( 18 ) Quantifying the dose of deep UV-LED to inactivate SARS-CoV-2 99.9% (3-log) ( 19 ) Establishing the persistence of SARS-CoV-2 on inanimate surfaces following UVC 99.99% (4-log) ( 20 ) Determining the effect of UVC on SARS-CoV-2 inoculated N95 respirators depending on material/model type 99.999% (5-log) in facepieces and straps of all tested N95 respirators ( 21 ) Developing an ultra‐high power UVC irradiation source to sterilize SARS‐CoV‐2 100% ( 22 ) Investigating UVC on SARS-CoV-2 in wet and dried surfaces > 99.9% (3-log) in 9 s and 4 s for wet and dried surfaces, respectively …”

“…Regarding the UVC system, eight used wavelengths at 254 nm ( 10 , 11 , 12 , 13 , 14 , 19 , 20 , 22 ), two at 222 nm ( 15 , 16 ), one at 280 nm ( 17 ), one at 265 nm, and 280 nm ( 18 ), and one at 275 nm ( 21 ). We also noticed that different UVC-based technologies were used.…”

“…We also noticed that different UVC-based technologies were used. Three studies were carried out with LED ( 17 , 18 , 21 ), while ten reported the use of lamps. From these, eight studies were performed with a mercury lamp ( 10 , 11 , 12 , 13 , 14 , 19 , 20 , 22 ), and two used krypton-chloride excimer lamps ( 15 , 16 ) ( Table 2 ).…”

Efficacy of frontline chemical biocides and disinfection approaches for inactivating SARS-CoV-2 variants of concern that cause coronavirus disease with the emergence of opportunities for green eco-solutions

“… SARS-CoV-2 (Hu/DP/Kng/19-020 strain) 4 log TCID 50 assay using VeroE6-TMPRSS2 cells [ 56 ] Glutaraldehyde 0.5%, 2 min, suspension test SARS‐CoV isolate FFM‐1 3 log TCID using human embryonic lung fibroblasts [ 23 ] Formaldehyde 0.7–1%, 2 min, suspension test Povidone iodine 1–2.5%, 15 secs, suspension testing of oral mouth wash SARS-CoV-2, USA-WA1/2020 strain 4 log TCID assay using Vero 76 cells [ 54 ] Technologies Steam sterilisation 121 o C, 5 min, medical masks, N95 respirators Avian coronavirus (H120) 2 log inoculation of embryonated eggs, real‐time TaqMan RT‐PCR assay [ 57 ] Heat 56 o C, 30 min, 65 o C, 15 min, 98 °C 2 min, suspension test. SARS-CoV-2 5 log TCID 50 assay using Vero E6 cells, [ 58 ] Deep UV LED 265, 280, and 300 nm, 20 second, hard surfaces, carrier test SARS-CoV-2 3.3 log Plaque assay using Vero E6 cells [ 59 ] Simulated sunlight 60 min on hard surfaces, carrier test on surface dried droplets. SARS-CoV-2 USA-WA1/2020 4 log.…”