Effectiveness of near-UVA in SARS-CoV-2 inactivation

This experimental study aimed to determine the activity of a near-UVA (405 nm) LED ceiling system against the SARS-CoV-2 virus. The ceiling system comprised 17 near-UVA LED lights with a radiant power of 1.1 W/each centred at 405 nm wavelength. A 96-multiwell plate, fixed to a wooden base, was inoculated with suspensions of VERO E6 cell cultures infected with SARS-CoV-2 virus and irradiated at a distance of 40 cm with a dose of 20.2 J/cm² for 120 min. The collected suspensions were transferred to VERO cell culture plates and incubated for 3 days. The maximum measurable log reduction obtained, starting from a concentration of 10^7.2 TCID50/mL, was 3.0 log₁₀ and indicated inhibition of SARS-CoV-2 replication by the near-UVA LED ceiling system. Near-UVA light at a 405-nm wavelength is emerging as a potential alternative treatment for localised infections and environmental decontamination because it is far less harmful to living organisms' cells than UV-C irradiation.