Evaluation of the virucidal efficacy of Klaran UVC LEDs against surface dried norovirus

Mariita, Richard M.; Wilson Miller, Amy C.; Randive, Rajul V.

Human norovirus (HuNoV) is a highly contagious pathogenic virus that is transmitted through contaminated food, water, high-touch surfaces and aerosols. Globally, there are an estimated 685 million infections annually due to norovirus, among them 200 million children under the age of 5, causing approximately 50,000 child deaths per year and costing an estimated $60 billion annually in healthcare. In the USA, HuNoV is responsible for 19-21 million illnesses, with an average of 570-800 deaths per year. HuNoV is especially pernicious because it requires less than 100 viral particles to cause an infection, and there are few effective disinfectants. It is believed that Ultraviolet Subtype C (UVC) irradiation might prove to be an effective disinfectant. This study seeks to determine the inactivation profile of UVC against norovirus using a Klaran UVC Light-emitting diode (LED) array product number KL265-50V-SM-WD, emitting radiation at 269 nm peak wavelength and a measured fluence of 1.25 mW/cm2 at a 7 cm source-surface distance. Since the HuNoV cannot currently be propagated in cell cultures, the study utilized feline calicivirus (FCV), a recommended surrogate as challenge organism. The test followed Modified ASTM E2197. Assessment of virus inactivation was performed using plaque assay method, with Crystal Violet as a staining agent to enhance plaque visualization. Within 18 seconds of exposure time at a UVC irradiance of 1.25mW/cm2 and a dose of 22.5 mJ/cm2, the study obtained 99.9 % virus reduction (3 log reduction value). These results demonstrate that Klaran UVC-LED array (KL265-50V-SM-WD) can provide effective inactivation of HuNoV.