UV-C irradiation-based inactivation of SARS-CoV-2 in contaminated porous and non-porous surfaces

Abstract

The SARS-CoV-2 pandemic emphasized effective cleaning and disinfection of common spaces as an essential tool to mitigate viral transmission. To address this problem, decontamination technologies based on UV-C light are being used. Our aim was to generate coherent and translational datasets of effective UV-C-based SARS-CoV-2 inactivation protocols for the application on surfaces with different compositions. Virus infectivity after UV-C exposure of several porous (bed linen, various types of upholstery, synthetic leather, clothing) and non-porous (types of plastic, stainless steel, glass, ceramics, wood, vinyl) materials was assessed through plaque assay using a SARS-CoV-2 clinical isolate. Studies were conducted under controlled environmental conditions with a 254-nm UV-C lamp and irradiance values quantified using a 254 nm-calibrated sensor. From each material type (porous/non-porous), a product was selected as a reference to assess the decrease of infectious virus particles as a function of UV-C dose, before testing the remaining surfaces with selected critical doses. Our data show that UV-C irradiation is effectively inactivating SARS-CoV-2 on both material types. However, an efficient reduction in the number of infectious viral particles was achieved much faster and at lower doses on non-porous surfaces. The treatment effectiveness on porous surfaces was demonstrated to be highly variable and composition-dependent. Our findings will support the optimization of UV-C-based technologies, enabling the adoption of effective customizable protocols that will help to ensure higher antiviral efficiencies.

Keywords: COVID-19; Non-porous surfaces; Porous surfaces; SARS-CoV-2; UV-C irradiation; Viral inactivation.

Fig. 1

(A) Scheme illustrating the positioning of samples, UV-C source, and measurement devices (UV-C sensor and datalogger) during UV-C treatment. (B) Top view of sample and sensor setup during treatment, showing their central positioning underneath the UV-C lamp (dashed area in A). (C) Main steps to quantify infectious virus particles, including sample washing and dilution steps, SARS-CoV-2 inoculation of Vero cell monolayers and reading of plaque assay results.

Fig. 2

Dose-response behaviour for polystyrene samples (representative non-porous surface). Bars represent infectious virus particles numbers recovered from the sample after respective irradiation times in relation to the control (no UV-C exposure). Yellow dots and line represent corresponding percentages of viral inactivation. Data are presented as mean ± standard deviation. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 3

Dose-response behaviour for car upholstery samples (representative porous surface). Bars represent infectious virus particle numbers recovered from the sample after respective irradiation times in relation to the control (no UV-C exposure). Yellow dots and line represent corresponding percentages of viral inactivation. Data are presented as mean ± standard deviation. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 4

Inactivation kinetics of SARS-CoV-2 promoted by UV-C radiation. Survival values are presented for: (A) polystyrene and (B) car upholstery. Data are presented as mean ± standard deviation. Non-linear regression applied to the inactivation kinetics data yielded LD₉₀ and T values of 0.85 mJ/cm² and 0.61, respectively, for polystyrene (R² = 0.97), and 119.2 mJ/cm² and 0.51, respectively, for car upholstery (R² = 0.98).

Fig. 5

Inactivation results using critical doses of 132, 264 and 396 mJ/cm² on tested porous surfaces: (A) bus upholstery, (B) synthetic leather, (C) hospital bed linen, (D) clothing fabric #1 and (E) #2. Bars represent infectious virus particle numbers recovered from the sample after respective irradiation times in relation to the control (no UV-C exposure). Yellow dots and line represent corresponding percentages of viral inactivation. Additionally, analysed doses are highlighted in grey. Data are presented as mean ± standard deviation. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)