Like many respiratory viruses, including flu, SARS-CoV-2 can be spread in tiny droplets released from the nose and mouth of an infected person as they cough. A single cough can produce up to 3,000 droplets. These particles can land on other people, clothing and surfaces around them. Besides, there is also some evidence that the virus is also shed for longer in fecal matter, so anyone not washing their hands thoroughly after visiting the toilet could contaminate anything they touch.
In this way, one aspect that has been unclear is exactly how long SARS-CoV-2, can survive outside the human body. Some studies on other coronaviruses, including SARS and MERS, found they can survive on metal, glass and plastic for as long as nine days, unless they are properly disinfected. Some can even hang around for up to 28 days in low temperatures.
Nevertheless, according to a new study conducted by US researchers, it seems SARS-CoV-2 ―the coronavirus responsible for the disease COVID-19―, can remain intact on surfaces for anywhere up to 72 hours. However, the precise figure depends heavily on the type of surface infected droplets land on, and might also rely on the density of virus particles in the spray, and other environmental conditions, such as temperature and sunlight (previous research examining the literature on animal and human strains of coronavirus provided insight into the virus’ ability to keep its integrity as it moves through the environment but, until now, experimental evidence on new SARS-CoV-2 has been limited).
Moreover, authors also tested for comparison the virus behind the 2003 SARS epidemic ―SARS-CoV-1―, with strains of both pathogens sprayed as micrometre-sized droplets onto various surfaces including cardboard, copper, and plastic.
Dropped onto plastic, the two virus strains appear to be able to stay intact far longer. Only half of the SARS-CoV-2 particles broke apart in just under seven hours, for example, with viable coronavirus particles still detected up to three days later.
Stainless steel was almost as bad, with a half-life for SARS-CoV-2 of 5.6 hours.
Copper, on the other hand, failed to provide similar protection for either strain, with the number of viable particles capable of causing disease vanishing within just four hours for SARS-CoV-2, and eight hours for SARS-CoV-1.
Similarly, on cardboard, no viable SARS-CoV-2 particles could be found after 24 hours, or SARS-CoV-1 after eight.
However, there are still a number of variables to keep in mind. Variations in individual results show how much the timing is affected by subtle differences. Besides, the laboratory was also kept at a fairly consistent 21 to 23 degrees Celsius, and 65 percent humidity. Just how this latest virus behaves in other conditions of lighting, humidity, and temperature is left to be seen.
Finally, the study reaffirms the need to disinfect surfaces with 0.1% sodium hypochlorite or 62–71% ethanol ―especially those made of plastic and stainless steel―, where possible. In addition, after touching any of these surfaces, it’s important to wash your hands with soap and water or alcohol-based hand rubs.
Link to the paper: https://doi.org/10.1056/NEJMc2004973
Editorial Disclaimer: information published during the 2020 COVID-19 pandemic may be updated frequently to reflect the dynamic nature of current understanding.
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