SARS-CoV-2 inactivation by ultraviolet radiation and visible light is dependent on wavelength and sample matrix.

Numerous studies have demonstrated that SARS-CoV-2 can be inactivated by ultraviolet (UV) radiation. However, there are few data available on the relative efficacy of different wavelengths of UV radiation and visible light, which complicates assessments of UV decontamination interventions. The present study evaluated the effects of monochromatic radiation at 16 wavelengths from 222 nm through 488 nm on SARS-CoV-2 in liquid aliquots and dried droplets of water and simulated saliva. The data were used to generate a set of action spectra which quantify the susceptibility of SARS-CoV-2 to genome damage and inactivation across the tested wavelengths. UVC wavelengths (≤280 nm) were most effective for inactivating SARS-CoV-2, although inactivation rates were dependent on sample type. Results from this study suggest that UV radiation can effectively inactivate SARS-CoV-2 in liquids and dried droplets, and provide a foundation for understanding the factors which affect the efficacy of different wavelengths in real-world settings.

Ultraviolet Radiation Technologies and Healthcare-Associated Infections: Standards and Metrology Needs.

The National Institute of Standards and Technology (NIST) hosted an international workshop on ultraviolet-C (UV-C) disinfection technologies on January 14-15, 2020, in Gaithersburg, Maryland, in collaboration with the International Ultraviolet Association (IUVA). This successful public event, as evidenced by the participation of more than 150 attendees, with 65% from the ultraviolet technology industry, was part of an ongoing collaborative effort between NIST and the IUVA and its affiliates to examine the measurement and standards needs for pathogen abatement with UV-C in the healthcare whole-room environment. Prior to and since this event, stakeholders from industry, academia, government, and public health services have been collaboratively engaged with NIST to accelerate the development and use of accurate measurements and models for UV-C disinfection technologies and facilitate technology transfer. The workshop served as an open forum to continue this discussion with a technical focus centered on the effective design, use, and implementation of UV-C technologies for the prevention and treatment of healthcare-associated infections (HAIs) in complex hospital settings. These settings include patient rooms, operating rooms, common staging areas, ventilation systems, personal protective equipment, and tools for the reprocessing and disinfecting of instruments or devices used in medical procedures, such as catheters and ventilators. The critical need for UV-C technologies for disinfection has been amplified by the outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (COVID-19), stimulating an even greater emphasis on identifying testing and performance metrology needs. This paper discusses these topics based on the international workshop and community activities since the workshop, including a public World-Wide-Web-based seminar with more than 500 registered attendees on September 30, 2020; an international conference on UV-C technologies for air and surface disinfection, December 8-9, 2020; and a webinar on returning to normalcy with the use of UV-C technologies, April 27 and 29, 2021. This article also serves as an introduction to a special section of the Journal of Research of the National Institute of Standards and Technology, where full papers address recent technical, noncommercial, UV-C technology and pathogen-abatement investigations. The set of papers provides keen insights from the vantage points of medicine and industry. Recent technical developments, successes, and needs in optics and photonics, radiation physics, biological efficacy, and the needs of future markets in UV-C technologies are described to provide a concise compilation of the community's efforts and the state of the field. Standards needs are identified and discussed throughout this special section. This article provides a summary of the essential role of standards for innovation and implementation of UV-C technology for improved patient care and public health.