Poster Presentation 12th Australasian Virology Society Meeting 2024

Inactivation of Airborne Virus Infectivity Using Ultraviolet Light Devices (#185)

Leo YY Lee 1 , Shane A Landry 2 , Milan Jamriska 3 , Dinesh Subedi 4 , Isabelle Magnin-Bougma 4 , Simon A Joosten 5 6 7 , Jeremy J Barr 4 , Kevin Kevin 8 , Robyn Schofield 9 , Jason Monty 8 , Kanta Subbarao 1 10
  1. Department of Microbiology and Immunology, The University of Melbourne, The Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia
  2. Department of Physiology, School of Biomedical Sciences & Biomedical Discovery Institute, Monash University, Melbourne, VIC, Australia
  3. Defence Science and Technology Group, Fishermans Bend, VIC, Australia
  4. School of Biological Sciences, Monash University, Melbourne, VIC, Australia
  5. Monash Lung, Sleep, Allergy and Immunology, Monash Health, Clayton, VIC, Australia
  6. School of Clinical Sciences, Monash University, Melbourne, VIC, Australia
  7. Monash Partners, Epworth, VIC, Australia
  8. School of Mechanical Engineering, The University of Melbourne, Melbourne, VIC, Australia
  9. School of Geography, Earth and Atmospheric Sciences,, The University of Melbourne, Melbourne, VIC, Australia
  10. WHO Collaborating Centre for Reference and Research on Influenza, Victorian Infectious Diseases Reference Laboratory, The Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia

Introduction: Effective control of seasonal and pandemic respiratory viruses will benefit from strategies to mitigate airborne transmission of viruses. Germicidal ultraviolet (GUV) devices emitting 254nm light are known to disinfect surfaces contaminated by common pathogens but direct exposure can be hazardous to human eyes and skin. 222nm UV devices are being investigated as potentially safer alternatives for public disinfection, particularly to inactivate airborne viruses. We sought to measure the reduction of infectivity in viral aerosols exposed to 222nm and 254m UV emitters in a controlled experimental setting.  

Methods: We constructed a 90L air chamber equipped with modular panels for a commercial uvmedico 222nm GUV emitter (1335µW/m3 ), or an industrial 254nm mercury lamp (3235µW/m3). We generated nebulised viral aerosols for seasonal influenza (A/H3N2), SARS-CoV-2 (ancestral) and bacteriophage (phiX174) viruses and subjected them to timed exposures of 222nm or 254nm UV light. Irradiated aerosols were then collected using Sartorius MD8 air samplers and assessed for infectivity compared to non-irradiated controls by quantitative viral culture.  

Results: We generated viral aerosols containing 3.9-5.2 log10 infectious units in the sampling chamber. Following 15s exposure of 222nm GUV we observed 6.2-fold, 11.8-fold and 1.9-fold reductions of infectious virus in air samples for influenza, SARS-CoV-2 and bacteriophage, respectively. Using the 254nm device with higher power output resulted in 21.8-fold, 315.5-fold and 109.8-fold -fold reductions compared to controls, respectively. We found that extended 60s exposure with either device resulted in >1000-fold reductions of infectious virus for SARS-CoV-2 air samples.   

Conclusions: We measured the disinfection efficacy of 222nm and 254nm GUV devices on infectious influenza, SARS-CoV-2 and bacteriophage viruses, which each demonstrated different sensitivities to short-duration UV exposure while airborne. Our system uses real infectious viruses to test the effective irradiation thresholds for different GUV devices used to interrupt airborne viral transmission.