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Figure 1 Virucidal activity of WHO formulations I (85 % ethanol) and II (75 % 2-propanol) against SARS-CoV-2. WHO formulations I (A) and II (B) were tested for their efficacy in inactivating SARS-CoV-2. The concentrations of the WHO formulations ranged from 0 % to Efficient inactivation of SARS-CoV-2 by WHO-recommended hand rub 1 formulations and alcohols 2
Abstract
80 % with an exposure time of 30 seconds. Viral titers are displayed as 50 % tissue culture infectious dose 50 (TCID 50 /mL) values. Cytotoxic effects are displayed as dashed bars are and were calculated analogous to virus infectivity. RFs are included above the bar. The mean of two -three independent experiments with standard deviation are shown. LLOQ: lower limit of quantification. Top inserts: Regression analysis of the inactivation of SARS-CoV-2, bovine CoV (BCoV), SARS-CoV and MERS-CoV by WHO formulation I (A) and II (B). Depicted is the percentage of inactivation at different concentrations.
The copyright holder for this preprint (which was not peer-reviewed) is the . https://doi.org/10.1101/2020.03.10.986711 doi: bioRxiv preprint
. CC-BY-NC-ND 4.0 International license author/funder. It is made available under a The copyright holder for this preprint (which was not peer-reviewed) is the . https://doi.org/10.1101/2020. 03 The recent emergence of Severe acute respiratory syndrome coronavirus 2 (SARS-2 CoV-2) causing COVID-19 is a major burden for health care systems worldwide. It is 3 important to address if the current infection control instructions based on active 4 ingredients are sufficient. We therefore determined the virucidal activity of two 5 alcohol-based hand rub solutions for hand disinfection recommended by the World 6
Health Organization (WHO), as well as commercially available alcohols. Efficient 7 SARS-CoV-2 inactivation was demonstrated for all tested alcohol-based disinfectants. 8
These findings show the successful inactivation of SARS-CoV-2 for the first time and 9 provide confidence in its use for the control of COVID-19. The copyright holder for this preprint (which was not peer-reviewed) is the . https://doi.org/10.1101/2020.03.10.986711 doi: bioRxiv preprint 4 especially in the elderly or patients with comorbidities 4 . As of March 6 th 2020 there are 1 101604 globally confirmed cases and related 3460 deaths 5 . Health care experts suspect 2 that a global pandemic is inevitable mainly because human-to-human transmission of 3 SARS-CoV-2 is very efficient and infected individuals can transmit the virus without 4 or with only mild symptoms 4 . Given that so far, no therapeutics or vaccines are 5 available, virus containment and prevention of infection are of highest priority. 6
Effective hand hygiene is crucial to limit virus spread. Therefore, easily available but 7 efficient disinfectants are crucial. The World Health Organization's 'Guidelines for 8
Hand Hygiene in Health Care' suggests two alcohol-based formulations for hand 9 sanitization to reduce pathogen infectivity and spreading. These recommendations are 10 based on fast-acting and broad-spectrum of microbicidal activity, as well as easy 11 accessibility and safety 3 . We have previously shown that WHO formulation I and II 12 were able to inactivate the closely related SARS-CoV and MERS-CoV 6 Results 20 SARS-CoV-2 was highly susceptible to the WHO formulations (Fig. 1) . WHO 21 formulation I, based on 85 % ethanol, efficiently inactivated the virus with reduction 22 factors (RFs) of 5.9 and concentrations between 40 % -80 % (Fig. 1A) . Subsequent 23 regression analysis revealed similar inactivation profiles compared to SARS-CoV, 24 . CC-BY-NC-ND 4.0 International license author/funder. It is made available under a The copyright holder for this preprint (which was not peer-reviewed) is the . https://doi.org/10.1101/2020.03.10.986711 doi: bioRxiv preprint 1 pathogenic human CoVs (Fig. 1A) . WHO formulation II, which is based on 75 % 2 isopropanol, demonstrated a better virucidal effect at low concentrations, with 3 complete viral inactivation and RFs of 5 at a minimal concentration of 30 % (Fig. 4 1B) . The regression analysis showed an inactivation profile of SARS-CoV-2, which 5 was in between SARS-CoV, BCoV and MERS-CoV (Fig. 1B) . 6
Next, we addressed the susceptibility of SARS-CoV-2 against the individual 7 components of the WHO recommended formulations which are also the main 8 ingredients of commercially available hand disinfections. Both alcohols, ethanol (Fig. 9 2A) and 2-propanol ( Fig. 2B) were able to reduce viral titers in 30 s exposure to 10 background levels with RFs between 4.8 and 5.9 after 30 sec. Furthermore, we could 11
show that a minimal concentration of 30 % ethanol or 2-propanol is sufficient for viral 12 inactivation (Fig. 2) . The copyright holder for this preprint (which was not peer-reviewed) is the . https://doi.org/10.1101/2020.03.10.986711 doi: bioRxiv preprint
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