UVA radiation could be a significant contributor to sunlight inactivation of SARS-CoV-2

Abstract

Past experiments demonstrated SARS-CoV-2 inactivation by simulated sunlight; models have considered exclusively mechanisms involving UVB acting directly on RNA. However, UVA inactivation has been demonstrated for other enveloped RNA viruses, through indirect mechanisms involving the suspension medium. We propose a model combining UVB and UVA inactivation for SARS-CoV-2, which improves predictions by accounting for effects associated with the medium. UVA sensitivities deduced for SARS-CoV-2 are consistent with data for SARS-CoV-1 under UVA only. This analysis calls for experiments to separately assess effects of UVA and UVB in different media, and for including UVA in inactivation models.Lay summaryRecent experiments have demonstrated that SARS-CoV-2 is inactivated by simulated sunlight; however, there are still many unknowns, including the mechanism of action and which part of the light spectrum is principally responsible. Our analysis indicates the need for targeted experiments that can separately assess the effects of UVA and UVB on SARS-CoV-2, and that sunlight inactivation models may need to be expanded to also include the effect of UVA. A first UVA-inclusive model is also proposed here. These findings have implications for how to improve the safety of the built environment, and for the seasonality of COVID-19.

Solar UV-B/A radiation is highly effective in inactivating SARS-CoV-2

“…54 ). Particularly, the comparison between predictions ( 13) and actual measurements of Covid-19 exposure to artificial Solar radiation ( 54), suggested the importance of UV-A photons ( 16,17 ). Ratnesar-Schumate and collaborators ( 54) found that 6.8 min of continuous exposure of dried saliva-like concentrations of Covid-19 to simulated sunlight in summer at a latitude of 40 degrees were sufficient to inactivate 90% of virions.…”

“…In particular, about 10% of the photons emitted by the Sun in the range 290-315 nm (UV-B) and as much as 95% of those in the range 315-400 nm (UV-A), reach the Earth. The effect of these photons on Single-and Double-Stranded RNA/ DNA viruses [10][11][12][13] and the possible role they play on the seasonality of epidemics [14][15][16][17][18][19][20][21][22][23][24][25] , are nevertheless little studied and highly debated in alternative or complementarity to other environmental causes 23,[26][27][28][29][30][31][32][33][34][35][36][37][38][39] . Notably though, the effects of both direct and indirect radiation from the Sun needs to be considered in order to completely explain the effects of UV radiations in life processes (with e.g.…”

Solar UV–B/A Radiation is Highly Effective in Inactivating SARS-CoV-2

“…[54]). Particularly, the comparison between predictions ( [13]) and actual measurements of Covid-19 exposure to artificial Solar radiation ( [54]), suggested the importance of UV-A photons ( [16,17]). Ratnesar-Schumate and collaborators ( [54]) found that 6.8 minute of continuous exposure of dried saliva-like concentrations of Covid-19 to simulated sunlight in summer at a latitude of 40 degrees were sufficient to inactivate 90% of virions.…”

“…In particular, about 10% of the photons emitted by the Sun in the range 290-315 nm (UV-B) and as much as 95% of those in the range 315-400 nm (UV-A), reach the Earth. The effect of these photons on Single-and Double-Stranded RNA/DNA viruses [10][11][12][13] and the possible role they play on the seasonality of epidemics [14][15][16][17][18][19][20][21][22][23][24][25], are nevertheless little studied and highly debated in alternative or complementarity to other environmental causes [23,[26][27][28][29][30][31][32][33][34][35][36][37][38][39]. Notably though, the effects of both direct and indirect radiation from the Sun needs to be considered in order to completely explain the effects of UV radiations in life processes (with e.g.…”

Les dangers du SARS-CoV-2 pour les écosystèmes aquatiques

“…Les UV-A pourraient inactiver le SARS-CoV-2 par analogie au SARS-CoV-1 [ 48 ]. Cependant, Luzzatto-Fegiz et al recommandent la mise en place de recherches plus poussées et axées sur l’impact des UV-A dans l’inactivation du SARS-CoV-2 [ 48 ].…”