Journal of Photochemistry and Photobiology (Jun 2022)

UV and violet light can Neutralize SARS-CoV-2 Infectivity

  • Mara Biasin,
  • Sergio Strizzi,
  • Andrea Bianco,
  • Alberto Macchi,
  • Olga Utyro,
  • Giovanni Pareschi,
  • Alessia Loffreda,
  • Adalberto Cavalleri,
  • Manuela Lualdi,
  • Daria Trabattoni,
  • Carlo Tacchetti,
  • Davide Mazza,
  • Mario Clerici

Journal volume & issue
Vol. 10
p. 100107

Abstract

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We performed an in-depth analysis of the virucidal effect of discrete wavelengths: UV-C (278 nm), UV-B (308 nm), UV-A (366 nm) and violet (405 nm) on SARS-CoV-2. By using a highly infectious titer of SARS-CoV-2 we observed that the violet light-dose resulting in a 2-log viral inactivation is only 104 times less efficient than UV-C light. Moreover, by qPCR (quantitative Polymerase chain reaction) and fluorescence in situ hybridization (FISH) approach we verified that the viral titer typically found in the sputum of COVID-19 patients can be completely inactivated by the long UV-wavelengths corresponding to UV-A and UV-B solar irradiation. The comparison of the UV action spectrum on SARS-CoV-2 to previous results obtained on other pathogens suggests that RNA viruses might be particularly sensitive to long UV wavelengths. Our data extend previous results showing that SARS-CoV-2 is highly susceptible to UV light and offer an explanation to the reduced incidence of SARS-CoV-2 infection seen in the summer season.

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