Systematic evaluating and modeling of SARS-CoV-2 UVC disinfection

Abstract

The ongoing COVID-19 global pandemic has necessitated evaluating various disinfection technologies for reducing viral transmission in public settings. Ultraviolet (UV) radiation can inactivate pathogens and viruses but more insight is needed into the performance of different UV wavelengths and their applications. We observed greater than a 3-log reduction of SARS-CoV-2 infectivity with a dose of 12.5 mJ/cm2 of 254 nm UV light when the viruses were suspended in PBS, while a dose of 25 mJ/cm2 was necessary to achieve a similar reduction when they were in an EMEM culture medium containing 2%(v/v) FBS, highlighting the critical effect of media in which the virus is suspended, given that SARS-CoV-2 is always aerosolized when airborne or deposited on a surface. It was found that SARS-CoV-2 susceptibility (a measure of the effectiveness of the UV light) in a buffer such as PBS was 4.4-fold greater than that in a cell culture medium. Furthermore, we discovered the attenuation of UVC disinfection by amino acids, vitamins, and niacinamide, highlighting the importance of determining UVC dosages under a condition close to aerosols that wrap the viruses. We developed a disinfection model to determine the effect of the environment on UVC effectiveness with three different wavelengths, 222 nm, 254 nm, and 265 nm. An inverse correlation between the liquid absorbance and the viral susceptibility was observed. We found that 222 nm light was most effective at reducing viral infectivity in low absorbing liquids such as PBS, whereas 265 nm light was most effective in high absorbing liquids such as cell culture medium. Viral susceptibility was further decreased in N95 masks with 222 nm light being the most effective. The safety of 222 nm was also studied. We detected changes to the mechanical properties of the stratum corneum of human skins when the 222 nm accumulative exposure exceeded 50 J/cm2.The findings highlight the need to evaluate each UV for a given application, as well as limiting the dose to the lowest dose necessary to avoid unnecessary exposure to the public.

Preparing for the Next Pandemic: Predicting UV Inactivation of Coronaviruses with Machine Learning

“…The inactivation ability of UV at different wavelengths follows the order of UV 280 > UV 270 > UV 260 > UV 254 > UV 290 > UV 222 . The difference with our conclusion might be related to different absorption and scattering effects of different kinds of protein and suspended materials in the medium for UV irradiation at the same wavelength . For the dried samples, droplets of viral suspension were typically dried at room temperature in the air.…”

“…16 The difference with our conclusion might be related to different absorption and scattering effects of different kinds of protein and suspended materials in the medium for UV irradiation at the same wavelength. 40 For the dried samples, droplets of viral suspension were typically dried at room temperature in the air. Then the dried samples were resuspended to measure virus titers, thus excluding the titer reduction of samples during the drying process.…”

Viral, bacterial, and fungal contamination of Automated Teller Machines (ATMs)

“…The higher persistence of viruses in the confined space of the ATMs is likely due to the fact that shielded surfaces are not exposed to direct UV-C light and disinfectants that can, if not destroy, then at least effectively deactivate these viruses. Recent studies devoted to checking the ability of SARS-CoV-2 survival on inanimate surfaces, such as plastic, stainless steel and glass, revealed that UV-C irradiation is highly effective in inactivating SARS-CoV-2 replication, and thus can provide rapid, efficient, and sustainable sanitization of these surfaces [34,35,36,37].…”

UVC-Based Air Disinfection Systems for Rapid Inactivation of SARS-CoV-2 Present in the Air

“…This suggests that control measures must be taken beyond personal hygiene. UVC radiation is already well known to effectively kill bacteria and viruses [ 11 ] and recent studies have shown that this method is effective in inactivating the SARS-CoV-2 virus [ 12 , 13 , 14 , 15 , 16 ]. UVC light causes the formation of pyrimidine dimers in the genetic material and inhibits transcription and replication [ 17 , 18 ].…”