Direct inactivation of SARS‐CoV‐2 by low level blue photobiomodulation LED at 470, 454 and 450 nm

Abstract

Blue light has been already reported as able to counteract different types of microorganisms including Gram‐positive and Gram‐negative bacteria, fungi and viruses, especially the enveloped ones. It has been reported that both blue and visible light can efficiently impact SARS‐CoV‐2 by affecting its ability to replicate in in vitro cellular models of infection. In this study, blue light at 450, 454 and 470 nm was tested on SARS‐CoV‐2 to evaluate the residual viral infectious potential on Vero E6, Caco‐2 and Calu‐3 cells, after the irradiation of viral particles. Following 12' of irradiation at 40 mW/cm2, a drastic block of viral amplification was observed. Indeed, at 7 days post‐irradiation/infection the viral load was the same as the one measured 1 day post‐irradiation/infection, and cellular viability was maintained showing similar levels to the noninfected control cells. Taken together our results indicate that blue LED lamps can be considered as a cheap and convenient tool for SARS‐CoV‐2 disinfection.

Effect of near‐infrared and blue laser light on vero E6 cells SARS‐CoV‐2 infection model

“…Our results agree with our previous findings [12,13], which reported that blue laser light at not cytotoxic doses is able to block viral replication with long-lasting (7 days) effect. In our previous paper [12] employing an LED device, inhibition of virus replication was observed at 24 and 48 h post irradiation, while at 72 h, although a negative trend was found, it did not reach the statistical significance.…”

“…These observations were not in agreement with our previous findings [ 13 ] where a reduction of intact virions was determined, nevertheless, the different devices, blue LED lamps in the previous study and class IV medical laser in the current one can account for the divergent outcomes; moreover, the protocols employed in the previous study were slightly cytotoxic [ 13 ], while the current ones, both employing NIR or blue wavelengths, did not have any impact on cells' survival.…”

“…Instead, in the present work, a complete block of viral replication was detected; indeed the viral titer was the same between day 3 and day 7, both when the virus was irradiated itself or the photons were delivered on already infected cells. In our second article [ 13 ], utilizing the same LED instrument of the first work, a suppression of SARS‐CoV‐2 expansion was demonstrated, exploiting a protocol that resulted slightly cytotoxic with 80% of viable cells after irradiation, while in the current work, no harmful effect was detected on cell survival by blue PBMT, while revealing a strong antiviral impact.…”

“…Several studies showed that PBMT at the blue wavelength possesses an inhibitory effect on Severe Acute Respiratory Syndrome Coronavirus‐2 (SARS‐CoV‐2) replication [ 9 , 10 , 11 , 12 , 13 ].…”

The inhibitory and inactivating effects of visible light on SARS-CoV-2: A narrative update

“…Similar dose dependent findings were observed for visible light delivered from LED peaking at 405 nm [17] . Inactivating effects of 420, 425, 450, 454 or 474 nm blue light upon SARS-CoV-2 virions (suspended in media) have been observed in subsequently infected Vero cells [ 6 , 18 , 19 ] as well Caco-2 (colon carcinoma) and Calu-3 cells (non-small-cell lung cancer) [19] . Blue light (425 nm) from an LED array inactivated a range of SARS-CoV-2 variants (WA1, Alpha, Beta, Delta, Gamma, Lambda, and Omicron) in a dose-dependent fashion [ 6 , 20 ].…”