Effect of intermittent irradiation and fluence-response of 222 nm ultraviolet light on SARS-CoV-2 contamination

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 ).…”

“… Reference Purpose UVC outcome for SARS-CoV-2 titer reduction ( 10 ) Identifying UVC lethal doses for SARS-CoV-2 90% (1-log) to 99.999% (5-log) ( 11 ) Identifying UVC lethal doses depending on SARS-CoV-2 concentration > 99.99% (4-log) ( 12 ) Evaluating and comparing the sterilizing capability of UVC and ozone on SARS-CoV-2 adsorbed on different materials UVC: 99.9% (3-log) on glass, plastic, and gauze; 90% (1-log) on fleece; 94.4% (>1-log) for wool; 0% for wood. 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 >...…”

“…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.…”

“…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 ). Yet, 12 studies used continuous-wave emission regimen (CW) whereas one compared CW with intermittent UV light ( 16 ).…”

“…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 ). Yet, 12 studies used continuous-wave emission regimen (CW) whereas one compared CW with intermittent UV light ( 16 ). The authors did not observe expressive differences for SARS-CoV-2 inactivation between those regimes ( Table 2 ).…”