Stability of SARS-CoV-2 in different environmental conditions
Authors: Reza Dehbandi, Mohammad Ali Zazouli
Journal: The Lancet Microbe (2020)

We feel the need to address several errors in the findings presented in the Correspondence by Alex W H Chin and colleagues.1Chin AWH Chu JTS Perera MRA et al.Stability of SARS-CoV-2 in different environmental conditions.Lancet Microbe. 2020; 1: e10Summary Full Text Full Text PDF PubMed Scopus (925) Google Scholar Some results of this research challenge the current hand hygiene programmes recommended by different public health authorities, and we think that caution is required when applying those results to protect human health during infectious disease outbreaks, including the outbreak of COVID-19. It has been shown that unmedicated soap and water appears to be highly effective in removing influenza virus2Collignon PJ Carnie JA Infection control and pandemic influenza.Med J Aust. 2006; 185: S54-S57PubMed Google Scholar, 3Grayson ML Melvani S Druce J et al.Efficacy of soap and water and alcohol-based hand-rub preparations against live H1N1 influenza virus on the hands of human volunteers.Clin Infect Dis. 2009; 48: 285-291Crossref PubMed Scopus (183) Google Scholar and inactivating coronaviruses.4Montville R Schaffner DW A meta-analysis of the published literature on the effectiveness of antimicrobial soaps.J Food Prot. 2011; 74: 1875-1882Crossref PubMed Scopus (30) Google Scholar, 5Sickbert-Bennett EE Weber DJ Gergen-Teague MF Sobsey MD Samsa GP Rutala WA Comparative efficacy of hand hygiene agents in the reduction of bacteria and viruses.Am J Infect Control. 2005; 33: 67-77Summary Full Text Full Text PDF PubMed Scopus (136) Google Scholar The combined action of soap and water effectively dissolves the fat membrane of the coronavirus as well as the glue that holds the virus together, detaching it from the surface (eg, skin) and causing it to fall apart like a house of cards.6Türsen Ü Türsen B Lotti T Coronavirus-days in dermatology.Dermatol Ther. 2020; (published online April 19.)https://doi.org/10.1111/dth.13438Crossref Scopus (16) Google Scholar The authors considered household soap a disinfectant, whereas regular household soaps are not disinfectants but are a more of a detergent or cleaner. Additionally, the US Environmental Protection Agency does not list soap solution as a disinfectant in the list of disinfectants for use against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).7United States Environmental Protection AgencyList N: disinfectants for use against SARS-CoV-2.https://www.epa.gov/pesticide-registration/list-n-disinfectants-use-against-sars-cov-2-covid-19Date accessed: May 4, 2020Google Scholar WHO's recommendations for cleaning practice suggest to clean surfaces with regular household soap or detergent before using household disinfectants such as 0·1% or 0·5% sodium hypochlorite.8WHOWater, sanitation, hygiene, and waste management for the COVID-19 virus: interim guidance.https://www.who.int/publications/i/item/water-sanitation-hygiene-and-waste-management-for-the-covid-19-virus-interim-guidanceDate: April 23, 2020Date accessed: May 2, 2020Google Scholar The applied method of research by Chin and colleagues1Chin AWH Chu JTS Perera MRA et al.Stability of SARS-CoV-2 in different environmental conditions.Lancet Microbe. 2020; 1: e10Summary Full Text Full Text PDF PubMed Scopus (925) Google Scholar to add SARS-CoV-2 culture to a prepared 0·1% soap solution is problematic. The results might imply that in order to inactive coronavirus using a soap solution, people should put their hands in a pan of hand soap solution for more than 5 minutes. This is different from what actually happens when people wash their hands with soap. We believe that the results of this research could thus be misleading, in terms of protective methods to be used against SARS-CoV-2. Besides, we were surprised to note that the authors did not specify the type of soap used in their tests, which is important factor in predicting its virucidal effects. It seems that the Correspondence also does not address the effects of shorter incubation times on virus activity. The virucidal effects of different disinfectants on SARS-CoV-2 were investigated with a number of incubation times (eg, 5, 15, and 30 min), and no infectious virus could be detected in all cases with the exception of a 5-min incubation with hand soap. However, the authors did not consider an incubation time of less than 5 min, for example 1 min or less. Data published in February and March of 2020 suggest effective inactivation of coronavirus with 62–71% ethanol, 0·5% hydrogen peroxide, 0·5% sodium hypochlorite, and 0·1% sodium hypochlorite within 1 min.9Kampf G Todt D Pfaender S Steinmann E Persistence of coronaviruses on inanimate surfaces and their inactivation with biocidal agents.J Hosp Infect. 2020; 104: 246-251Summary Full Text Full Text PDF PubMed Scopus (2121) Google Scholar, 10Kampf G Potential role of inanimate surfaces for the spread of coronaviruses and their inactivation with disinfectant agents.Infect Prev Pract. 2020; 2100044Crossref Scopus (96) Google Scholar Washing hands with soap and water for 40-60 s is also recommended in WHO's hand hygiene practices against enveloped viruses such as SARS-CoV-2.8WHOWater, sanitation, hygiene, and waste management for the COVID-19 virus: interim guidance.https://www.who.int/publications/i/item/water-sanitation-hygiene-and-waste-management-for-the-covid-19-virus-interim-guidanceDate: April 23, 2020Date accessed: May 2, 2020Google Scholar Commonly, the length of time required to carry out handwashing using soap and water is less than 1 min and the minimum is 20 s.6Türsen Ü Türsen B Lotti T Coronavirus-days in dermatology.Dermatol Ther. 2020; (published online April 19.)https://doi.org/10.1111/dth.13438Crossref Scopus (16) Google Scholar Therefore, it would have been more appropriate to test incubation times of less than 5 min, such as 10–50 s and 1–3 min to test the virucidal effects of soap. Lastly, the concentration and exposure time of antiseptics are important parameters for their efficacy. Chin and colleagues1Chin AWH Chu JTS Perera MRA et al.Stability of SARS-CoV-2 in different environmental conditions.Lancet Microbe. 2020; 1: e10Summary Full Text Full Text PDF PubMed Scopus (925) Google Scholar applied chlorinated homemade bleach solutions at a concentration of 0·1% and 0·05%, using the same incubation times starting at 5 min. The results indicated similar efficiency of inactivation of SARS-CoV-2 for both concentrations. Since both of these disinfectant solutions can inactivate the virus in less than 1 min,9Kampf G Todt D Pfaender S Steinmann E Persistence of coronaviruses on inanimate surfaces and their inactivation with biocidal agents.J Hosp Infect. 2020; 104: 246-251Summary Full Text Full Text PDF PubMed Scopus (2121) Google Scholar, 10Kampf G Potential role of inanimate surfaces for the spread of coronaviruses and their inactivation with disinfectant agents.Infect Prev Pract. 2020; 2100044Crossref Scopus (96) Google Scholar an incubation time of 5 min or more means they were not able to differentiate the effect of each of these concentrations on the stability of the virus. Again, it would have been more appropriate to test incubation times of less than 5 min instead. We declare no competing interests. Stability of SARS-CoV-2 in different environmental conditions – Authors' replyReza Dehbandi and Mohammad Ali Zazouli query our Correspondence about the stability of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in different environmental conditions.1 Rather than testing the cleansing properties of the studied disinfectants, the objective of our work was to reveal the virucidal effects of these disinfectants, specifically their ability to inactivate SARS-CoV-2. We entirely agree with Dehbandi and Zazouli that hand hygiene is a key topic that can help to reduce SARS-CoV-2 transmission. Full-Text PDF Open AccessStability of SARS-CoV-2 in different environmental conditionsWe previously reported the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in different clinical samples.1 This virus can be detected on different surfaces in a contaminated site.2 Here, we report the stability of SARS-CoV-2 in different environmental conditions. 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