Sunlight Inactivation of Influenza A Virus and Bacteriophages on an Acrylic Surface

Seasonal epidemics and pandemics of influenza cause a large public health burden, with transmission occurring via contact with contaminated fomites. Sunlight has been shown to inactivate viruses in water, but its effect on viruses on surfaces remains poorly understood. This study investigated the inactivation of bacteriophage MS2, bacteriophage Phi6, and influenza A virus H1N1 (IAV) on an acrylic surface exposed to both natural and simulated sunlight. Findings demonstrate that sunlight can rapidly inactivate viruses on an acrylic surface, with the time required for 99% inactivation ranging from 2.1 to 4.2 h for MS2, 0.72 to 0.83 h for Phi6, and 0.26 to 0.35 h for IAV. Human saliva protected MS2 against sunlight inactivation relative to its inactivation in laboratory buffer but had no effect on Phi6 and IAV. IAV exhibited similar inactivation rate constants under natural and simulated sunlight. We assessed IAV RNA genome damage under sunlight using droplet digital reverse transcriptase-polymerase chain reaction targeting all eight gene segments. The extrapolated whole genome decay overestimated the IAV infectivity loss, suggesting limitations of using a single-hit model for IAV RNA sunlight photodamage. Results indicate that natural sunlight can substantially reduce the survival of the influenza virus on surfaces, thereby lowering the fomite-mediated transmission of respiratory disease in sunlit environments.