Ultrafast inactivation of SARS-CoV-2 by 254-nm UV-C irradiation on porous and non-porous media of medical interest using an omnidirectional chamber

Abstract

Covid-19 has spurred a renewed interest in decontamination techniques for air, objects and surfaces. Beginning in 2020, urgent effort was done to permit the reuse of UV-C for inactivating SARS-CoV-2. However, those studies diverged widely on the dose necessary to reach this goal; until today, the real value of the sensitivity of the virus to a 254-nm illumination is not known precisely. In this study, decontamination was performed in an original UV-C large decontamination chamber (UVCab, ON-LIGHT, France) delivering an omnidirectional irradiation with an average dose of 50 mJ/cm² in 60 s. Viral inactivation was checked by both cell culture and PCR test. SARS-CoV-2 was inactivated by UV-C light within 3 s on both porous (disposable gown) and non-porous (stainless steel and apron) surfaces. For the porous surface, an irradiation of 5 min was needed to achieve a completely negative PCR signal. The Z value estimating the sensitivity of SARS-CoV-2 to UV-C in the experimental conditions of our cabinet was shown to be > 0.5820 m²/J. These results illustrate the ability of this apparatus to inactivate rapidly and definitively high loads of SARS-CoV-2 deposited on porous or non-porous supports and opens new perspectives on material decontamination using UV-C.

Figure 1

Inactivation of SARS-CoV-2 after exposure to different UV-C doses. Representation of viral inactivation by PCR technique on different surfaces (gown, apron, stainless steel) subjected to increasing doses of UV-C irradiation. (A) All surfaces, (B) Disposable gown, (C) Aprons, (D) Stainless steel (horizontal), (E) Stainless steel (vertical). Error bars show standard deviation.

Figure 2

Illustration of the effect of planar vs omnidirectional illumination of dried virus solution. Black: substrate; Red: SARS-CoV-2 virions; Green: vestigial proteins from culture media. (A) Planar illumination leads to shadowing by proteins and virions. (B) Omnidirectional illumination eliminates shadowing.