PD05: Skin safety and efficacy of filtered far ultraviolet C for SARS‐CoV‐2 inactivation

Abstract

Skin safety and efficacy of filtered far ultraviolet C for SARS-CoV-2 inactivation E. Eadie, R.P. Hickerson, M.J. Conneely, R. Hammond, S.K.H. Tsutsumi, C.P. Cabrera, A. Wood, A.W. Longbottom, A.J. Parker, S.H. Ibbotson and K. Wood Photobiology Unit, NHS Tayside, Dundee, UK; School of Life Sciences and Photobiology Unit, University of Dundee, Dundee, UK; Ten Bio Ltd, Dundee, UK; School of Medicine and SUPA, School of Physics & Astronomy, University of St Andrews, St Andrews, UK; and Fluid Gravity Engineering Ltd, St Andrews, UK Excimer lamps have a peak emission wavelength of 222 nm [far ultraviolet (UV)C] and have been shown in laboratory settings to inactivate SARS-CoV-2, the virus responsible for the COVID-19 pandemic. As a result, lamps are being installed worldwide to disinfect air in occupied rooms. It is claimed that this will reduce COVID-19 transmission and that the lamps are ‘safe for humans’. These claims are based predominantly on laboratory, animal and limited human studies. It was our aim to gather more evidence on both the real-world efficacy and skin safety of this short wavelength UVC radiation. We used a two-pronged research approach: (i) generation of skin safety data investigating DNA damage, immunosuppression and modifications to the skin microbiome – the innovative TenSkin model was used to rapidly generate these data; and (ii) computational fluid dynamics combined with Monte Carlo radiative transfer computer modelling to simulate air flow, particle generation and far-UVC irradiation of a typical classroom. A classroom (12 m 9 6 m 9 3 m) with four air inlets, each 20 cm 9 20 cm, producing an inflow air speed of 2 5 m s was simulated. This is equivalent to six air changes per hour (ACH; typical classroom 5–7 ACH). With uniform release of particles, at a height of 0 5 m, the mechanical ventilation reduces the particle load to 6% in 30 min. The addition of 18 commercially available far-UVC lamps located in the ceiling, irradiating the room below, resulted in reduction to 3% at 30 min. Far-UVC lamps with a larger angular distribution would reduce the particle load to 0 1% at 30 min. These simulations have a restriction on exposure at 2 m that is equivalent to the legal limits of the Artificial Optical Radiation Regulations 2010. For context, irradiation of the TenSkin model with a filtered far-UVC lamp demonstrated minimal cyclobutane pyrimidine dimer formation at a dose 260 times higher than current legal limits, and this was restricted to the most superficial nonproliferating epidermal cells. The classroom simulations were repeated with the irradiation restriction set at 20 and 100 times the exposure limits, which resulted in a 99 99% reduction of particle load within 4 5 min and 1 min, respectively. Filtered far-UVC lamps cause minimal DNA damage, which is limited to the most superficial epidermal layers. There may be a case for increasing current exposure limits. Simulations suggest that appropriately deployed far-UVC will be a fast and effective public health control for inactivating SARS-CoV-2 in an occupied room. PD06 (P26) Using the Vitiligo Noticeability Scale in clinical trials and clinical practice: construct validity, interpretability, reliability and acceptability J. Batchelor, S. Gran, P. Leighton, L. Howells, A. Montgomery, W. Tan and K. Thomas University of Nottingham, Nottingham, UK Systematic reviews have identified many vitiligo trials, but these use different and often unvalidated outcome measures, preventing the combination of results in meta-analyses and leading to research waste. To address this problem, a vitiligo core outcome set (VCOS) is being developed. Core outcome sets are internationally agreed minimum sets of high-quality, validated outcome measurement instruments that should be used in clinical trials for specific conditions. Their adoption improves trial design and allows meta-analysis of data from different trials, generating better-quality evidence to support patient care. Valid and reliable outcome measures are needed for the VCOS. We previously developed the Vitiligo Noticeability Scale (VNS) as a patient-reported outcome measure to assess one of the domains in the VCOS: cosmetic acceptability of repigmentation achieved with vitiligo treatment. When developing the VNS we used digitally generated images to show different levels of repigmentation. In this research, we used a large database of clinical images of vitiligo from the HI-Light Vitiligo trial, in order to assess the construct validity, interpretability, test–retest reliability and acceptability of the VNS. We used image pairs of vitiligo patches before and after treatment, plus VNS and other outcome data, from the HI-Light trial. We compared these with outcome assessments for the same image pairs made by clinicians and people with vitiligo who were not trial participants. We conducted hypothesis testing to assess psychometric properties of the VNS, using kappa statistics to assess agreement between outcome measures. We also ran three focus groups and an online discussion group to gain qualitative feedback on how the VNS is used by people with vitiligo. Our hypothesis that there would be a positive association between VNS and global treatment success at end of treatment was supported. The kappa statistic ranged from 0 41 to 0 91, depending on the VNS score used to define treatment success. A VNS score of 3 (partial treatment response) may be more highly valued by people undergoing vitiligo treatment than previously thought. Age and skin phototype did not influence interpretation of the VNS scores. Other analyses confirmed VNS test–retest reliability (weighted kappa 0 73). Clinician-rated percentage repigmentation > 75% also showed good agreement with global treatment success (kappa 0 80). In the focus groups, people with vitiligo confirmed the VNS to be an acceptable and meaningful assessment. These findings support the case for including the VNS in the VCOS for the domain of ‘cosmetically acceptable repigmentation’.