Simulated sunlight decreases the viability of SARS-CoV-2

The novel coronavirus, SARS-CoV-2, has spread into a pandemic since its emergence in Wuhan, China in December of 2019. This has been facilitated by its high transmissibility within the human population and its ability to remain viable on inanimate surfaces for an extended period. To address the latter, we examined the ability of sunlight to degrade SARS-CoV-2 on stainless steel. All assays were performed using a solar simulator at the equivalent of one air mass (i.e. equatorial sun at its Zenith). Heat-controlled experiments were conducted at approximately 34% relative humidity (RH); otherwise, RH decreased with sunlight exposure until a constant temperature was maintained. When initially suspended in tissue culture medium, the virus was rendered non-viable after two hours of sunlight exposure. However, when suspended in an organic matrix designed to mimic bodily secretions, three hours of continuous sunlight was required for complete degradation. From this work, we demonstrate that sunlight represents an effective decontamination method but the speed of decontamination is variable based on the underlying matrix. This information has an important impact on the development of infection prevention and control protocols to reduce the spread of this deadly pathogen.