key: cord-0954167-uuqviae4
authors: Franke, Gefion; Knobling, Birte; Brill, Florian H.; Becker, Britta; Klupp, Eva M.; Campos, Cristina Belmar; Pfefferle, Susanne; Lütgehetmann, Marc; Knobloch, Johannes K.
title: An automated room disinfection system using ozone is highly active against surrogates for SARS-CoV-2
date: 2021-04-15
journal: J Hosp Infect
DOI: 10.1016/j.jhin.2021.04.007
sha: 368535472843e36266cbc38155988a88378e99b4
doc_id: 954167
cord_uid: uuqviae4

BACKGROUND: The presence of coronaviruses on surfaces in the patient environment is a potential source of indirect transmission. Manual cleaning and disinfection measures do not always achieve sufficient removal of surface contamination. This increases the importance of automated solutions in the context of final disinfection of rooms in the hospital setting. Ozone is a highly effective disinfectant which, combined with high humidity, is an effective agent against respiratory viruses. Current devices allow continuous nebulization for high room humidity as well as ozone production without any consumables. AIM: In the following study, the effectiveness of a fully automatic room decontamination system based on ozone was tested against bacteriophage Φ6 (phi 6) and bovine coronavirus L9, as surrogate viruses for the pandemic coronavirus SARS-CoV-2. METHODS: For this purpose, various surfaces (ceramic tile, stainless steel surface and furniture board) were soiled with the surrogate viruses and placed at two different levels in a gas-tight test room. After using the automatic decontamination device according to the manufacturer's instructions, the surrogate viruses were recovered from the surfaces and examined by quantitative cultures. Then, reduction factors were calculated. FINDINGS: The ozone-based room decontamination device achieved virucidal efficacy (reduction factor >4 log10) against both surrogate organisms regardless of the different surfaces and positions confirming a high activity under the used conditions. CONCLUSION: Ozone is highly active against SARS-CoV-2 surrogate organisms. Further investigations are necessary for a safe application and efficacy in practice as well as integration into routine processes.

The spread of viruses with pandemic potential due to indirect contact transmission is controgested as a surrogate for coronaviruses [16] [17] [18] [19] After an incubation period of 24 to 48 hours' cells were lysed by a rapid freeze/thaw cycle. 118 Cellular debris was removed and the supernatant was mixed with bovine serum albumin 119 (BSA) (final concentration: 0.3 g/L BSA). After each experiment an endpoint dilution assay 120 was performed. Therefore, the treated and untreated carriers were rinsed with 1 mL medium 121 without fetal calf serum (FCS). Remaining infectivity was determined by transferring 0.1 mL 122 of appropriate tenfold serial dilutions into eight wells of a microtitre plate with a preformed 123 monolayer of U373 cells (10-15 x 10 3 cells per well), beginning with the highest dilution. Be-124 fore addition of virus, cells were washed twice with Eagle`s minimum essential medium 125 (EMEM) and incubated for 3 h with 100µL EMEM with trypsin. Microtitre plates were incubat-126 ed at 37 °C in a 5 % CO 2 -atmosphere. The cytopathic effect was read by using an inverted 127 microscope after five days and the infective dose TCID 50 /mL was calculated. The tested ozone room disinfection system represents a safe and useful additional disinfec-215 tion method that can be implemented after the discharge of patients infected with contagious 216 and environmentally resistant pathogens such as SARS-CoV-2. However, due to toxicity of 217 ozone, doors, ventilation diffusers must be strictly sealed to prevent unintentional dissemina-218 tion [24] , resulting in an additional work load for the operating person. Additionally, due to the 219 generated water aerosol smoke detectors must also be covered to avoid unwanted alarms. 220

During the disinfection cycle a concept is needed, to prevent unauthorized room entrance 221 during disinfection process. with anteroom and bathroom [37] . Furthermore, in order to achieve conditions that are as 235 close to reality as possible, we did not use standardized but realistic room conditions for the 236 untreated control panels that prevailed at the time of the test. Spontaneous reductions that 237 could be caused by temperature and humidity fluctuations will therefore not be excluded and 

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