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

Area of Science:

• Virology
• Photobiology
• Infectious Diseases

Background:

• The susceptibility of SARS-CoV-2 to ultraviolet (UV) light is crucial for understanding transmission dynamics.
• Previous studies have indicated UV light's virucidal properties, but specific wavelength effects require further investigation.

Purpose of the Study:

• To evaluate the virucidal efficacy of discrete UV and violet light wavelengths against SARS-CoV-2.
• To compare the efficiency of different wavelengths and assess their potential for inactivating the virus in clinical samples.

Main Methods:

• Infection of SARS-CoV-2 with high titer.
• Exposure to discrete wavelengths: UV-C (278 nm), UV-B (308 nm), UV-A (366 nm), and violet (405 nm).
• Viral inactivation quantified using quantitative Polymerase Chain Reaction (qPCR) and fluorescence in situ hybridization (FISH).

Main Results:

• Violet light (405 nm) achieved a 2-log viral inactivation, 10^4 times less efficient than UV-C (278 nm).
• UV-A (366 nm) and UV-B (308 nm) wavelengths completely inactivated SARS-CoV-2 viral titers found in patient sputum.
• RNA viruses appear particularly sensitive to longer UV wavelengths.

Conclusions:

• SARS-CoV-2 is highly susceptible to UV light, with longer wavelengths like UV-A and UV-B demonstrating significant virucidal effects.
• The findings suggest a potential mechanism for reduced SARS-CoV-2 incidence during summer months due to solar UV irradiation.
• This research supports the use of specific light wavelengths for viral disinfection and offers insights into seasonal transmission patterns.