Abstract
We previously reported the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in different clinical samples.1Pan Y Zhang D Yang P Poon LLM Wang Q Viral load of SARS-CoV-2 in clinical samples.Lancet Infect Dis. 2020; (published online Feb 24.)https://doi.org/10.1016/S1473-3099(20)30113-4Summary Full Text Full Text PDF Scopus (1192) Google Scholar This virus can be detected on different surfaces in a contaminated site.2Ye G Lin H Chen L et al.Environmental contamination of the SARS-CoV-2 in healthcare premises: an urgent call for protection for healthcare workers.medRxiv. 2020; (published online March 16.) (preprint).DOI: 10.1101/2020.03.11.20034546Google Scholar Here, we report the stability of SARS-CoV-2 in different environmental conditions. We first measured the stability of SARS-CoV-2 at different temperatures. SARS-CoV-2 in virus transport medium (final concentration ∼6·8 log unit of 50% tissue culture infectious dose [TCID50] per mL) was incubated for up to 14 days and then tested for its infectivity (appendix p 1). The virus is highly stable at 4°C, but sensitive to heat. At 4°C, there was only around a 0·7 log-unit reduction of infectious titre on day 14. With the incubation temperature increased to 70°C, the time for virus inactivation was reduced to 5 mins. We further investigated the stability of this virus on different surfaces. Briefly, a 5 μL droplet of virus culture (∼7·8 log unit of TCID50 per mL) was pipetted on a surface (appendix p 1; ∼cm2 per piece) and left at room temperature (22°C) with a relative humidity of around 65%. The inoculated objects retrieved at desired time-points were immediately soaked with 200 μL of virus transport medium for 30 mins to elute the virus. Therefore, this recovery of virus does not necessarily reflect the potential to pick up the virus from casual contact. No infectious virus could be recovered from printing and tissue papers after a 3-hour incubation, whereas no infectious virus could be detected from treated wood and cloth on day 2. By contrast, SARS-CoV-2 was more stable on smooth surfaces. No infectious virus could be detected from treated smooth surfaces on day 4 (glass and banknote) or day 7 (stainless steel and plastic). Strikingly, a detectable level of infectious virus could still be present on the outer layer of a surgical mask on day 7 (∼0·1% of the original inoculum). Interestingly, a biphasic decay of infectious SARS-CoV-2 could be found in samples recovered from these smooth surfaces (appendix pp 2–7). 39 representative non-infectious samples tested positive by RT-PCR3Chu DKW Pan Y Cheng SMS et al.Molecular diagnosis of a novel coronavirus (2019-nCoV) causing an outbreak of pneumonia.Clin Chem. 2020; (published online Jan 31.)DOI:10.1093/clinchem/hvaa029Crossref PubMed Scopus (952) Google Scholar (data not shown), showing that non-infectious viruses could still be recovered by the eluents. We also tested the virucidal effects of disinfectants by adding 15 μL of SARS-CoV-2 culture (∼7·8 log unit of TCID50 per mL) to 135 μL of various disinfectants at working concentration (appendix p 1). With the exception of a 5-min incubation with hand soap, no infectious virus could be detected after a 5-min incubation at room temperature (22°C). Additionally, we also found that SARS-CoV-2 is extremely stable in a wide range of pH values at room temperature (pH 3–10; appendix p 1). Overall, SARS-CoV-2 can be highly stable in a favourable environment,4van Doremalen N Bushmaker T Morris DH et al.Aerosol and surface stability of SARS-CoV-2 as compared with SARS-CoV-1.N Engl J Med. 2020; (published online March 17.)DOI:10.1056/NEJMc2004973Crossref Scopus (6789) Google Scholar but it is also susceptible to standard disinfection methods. This work was supported by National Institute of Allergy and Infectious Diseases, National Institutes of Health (contract HHSN272201400006C). LLMP was supported by the Croucher Foundation. We declare no competing interests. Download .pdf (.63 MB) Help with pdf files Supplementary appendix Viral load of SARS-CoV-2 in clinical samplesAn outbreak caused by a novel human coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first detected in Wuhan in December 2019,1 and has since spread within China and to other countries. Real-time RT-PCR assays are recommended for diagnosis of SARS-CoV-2 infection.2 However, viral dynamics in infected patients are still yet to be fully determined. Here, we report our findings from different types of clinical specimens collected from 82 infected individuals. Full-Text PDF 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 feel the need to address several errors in the findings presented in the Correspondence by Alex W H Chin and colleagues.1 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. Full-Text PDF Open Access