Abstract
To overcome the ongoing coronavirus disease 2019 (COVID-19) pandemic, transmission routes, such as healthcare worker infection, must be effectively prevented. Ultraviolet C (UVC) (254 nm) has recently been demonstrated to prevent environmental contamination by infected patients; however, studies on its application in contaminated hospital settings are limited. Herein, we explored the clinical application of UVC and determined its optimal dose. Environmental samples (n = 267) collected in 2021 were analyzed by a reverse transcription-polymerase chain reaction and subjected to UVC irradiation for different durations (minutes). We found that washbasins had a high contamination rate (45.5%). SARS-CoV-2 was inactivated after 15 min (estimated dose: 126 mJ/cm2) of UVC irradiation, and the contamination decreased from 41.7% before irradiation to 16.7%, 8.3%, and 0% after 5, 10, and 15 min of irradiation, respectively (p = 0.005). However, SARS-CoV-2 was still detected in washbasins after irradiation for 20 min but not after 30 min (252 mJ/cm2). Thus, 15 min of 254-nm UVC irradiation was effective in cleaning plastic, steel, and wood surfaces in the isolation ward. For silicon items, such as washbasins, 30 min was suggested; however, further studies using hospital environmental samples are needed to confirm the effective UVC inactivation of SARS-CoV-2.
Highlights
Since December 2019, when the coronavirus disease 2019 (COVID-19) was first reported in Wuhan, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has continued to spread globally, regardless of the season [1]
Similar trends were obtained for the E, N, and RdRP genes, with the highest contamination rate found in the ward vs. intensive care unit (ICU) (8.8% vs. 2.6%, 15.7% vs. 1.7%, and 6.9% vs. 2.6%, respectively) and 0% in the buffer area
Surface contamination in SARS-CoV-2 isolation wards may have occurred without environmental cleaning, especially in those places where patients were admitted within 3 days with a nasal swab SARS-CoV-2 reverse transcription-polymerase chain reaction (RT-PCR) cycle threshold values (CtVs) < 25
Summary
Since December 2019, when the coronavirus disease 2019 (COVID-19) was first reported in Wuhan, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has continued to spread globally, regardless of the season [1]. Regarding HCW infections, the risk factors are exposure, non-use of personal protection equipment, workplace setting, and profession [5]. Environmental service workers in hospitals should observe the proper use of personal protection equipment and hand hygiene and note the influence of profession and knowledge on the contamination of patients’ living areas in the wards to lower their risk of getting infected. SARS-CoV-2 remains on surfaces after shedding, which increases the risk of transmission to HCWs [6]. SARS-CoV-2 is stable and detectable for up to 72 h on plastic, 48 h on stainless steel, 24 h on cardboard, and 4 h on copper [7]. SARS-CoV-2 was undetectable on glass and banknotes after four days and on stainless steel and plastic after seven days at room temperature (22 ◦C) and relative humidity of approximately 65% [8]
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