Inactivation of Severe Acute Respiratory Syndrome Coronavirus 2 by WHO-Recommended Hand Rub Formulations and Alcohols

Inactivation of Severe Acute Respiratory Syndrome Coronavirus 2 by WHO-Recommended Hand Rub Formulations and Alcohols Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the third highly pathogenic human coronavirus to cross the species barrier into the human population during the past 20 years (1–3). SARS-CoV-2 infection is associated with coronavirus disease (COVID-19), which is characterized by severe respiratory distress, fever, and cough and high rates of mortality, especially in older persons and those with underlying health conditions. Original WHO formulation I consists of 80% (vol/vol) ethanol, 1.45% (vol/vol) glycerol, and 0.125% (vol/vol) hydrogen peroxide. Original WHO formulation II consists of 75% (vol/vol) 2-propanol, 1.45% (vol/vol) glycerol, and 0.125% (vol/vol) hydrogen peroxide. The modified WHO formulation I used in our study consists of 80% (wt/wt) ethanol, 0.725% (vol/vol) glycerol, and 0.125% (vol/vol) hydrogen peroxide. The modified isopropyl-based WHO formulation II contains 75% (wt/wt) 2-propanol, 0.725% (vol/vol) glycerol, and 0.125% (vol/vol) hydrogen peroxide (9). We also prepared ethanol (CAS 64–17–5) and 2-propanol (CAS 67–63–0) in vol/vol dilutions for investigation. We performed virucidal activity studies by using a quantitative suspension test with 30 s exposure time (6). In brief, we mixed 1 part virus suspension with 1 part organic load (0.3% bovine serum albumin as an interfering substance) and 8 parts disinfectant solution of different concentrations. After a 30 s exposure, we serially diluted samples and determined the 50% tissue culture infectious dose (TCID50) per milliliter by using crystal violet staining and subsequently scoring the number of wells displaying cytopathic effects. We calculated TCID50 by the Spearman-Kärber algorithm, as described Our results showed that SARS-CoV-2 was highly susceptible to the original and the modified WHO formulations (Figure 1). The original and modified versions of formulation I efficiently inactivated the virus. We found that SARS-CoV-2 was efficiently inactivated by WHO-recommended formulations, supporting their use in healthcare systems and viral outbreaks. Of note, both the original and modified formulations were able to reduce viral titers to background level within 30 s. In addition, ethanol and 2-propanol were efficient in inactivating the virus in 30 s at a concentration of >30% (vol/vol). Alcohol constitutes the basis for many hand rubs routinely used in healthcare settings. One caveat of this study is the defined inactivation time of exactly 30 s, which is the time recommended but not routinely performed in practice. Our findings are crucial to minimize viral transmission and maximize virus inactivation in the current SARS-CoV-2 outbreak. To read more- https://wwwnc.cdc.gov/eid/article/26/7/20-0915_article

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