A novel human coronavirus that is now named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in Wuhan, China, in 2019 and is now causing a pandemic. In a new study, a team of U.S. scientists analyzed the aerosol and surface stability of SARS-CoV-2, which causes COVID-19 disease, and compared it with SARS-CoV-1, the most closely related human coronavirus. They found that SARS-CoV-2 was detectable in aerosols for up to 3 hours, up to 4 hours on copper, up to 24 hours on cardboard and up to 2-3 days on plastic and stainless steel. The results provide key information about the stability of SARS-CoV-2 and suggest that people may acquire the virus through the air and after touching contaminated objects.
This transmission electron microscope image shows SARS-CoV-2 isolated from a patient in the U.S. Image credit: NIAID-RML.
Myndi Holbrook fromn the National Institute of Allergy and Infectious Diseases, Hamilton, and colleagues compared how the environment affects SARS-CoV-2 and SARS-CoV-1.
SARS-CoV-1, which causes SARS, emerged from China and infected more than 8,000 people in 2002 and 2003.
SARS-CoV-1 was eradicated by intensive contact tracing and case isolation measures and no cases have been detected since 2004.
In the stability study the two viruses behaved similarly, which unfortunately fails to explain why COVID-19 has become a much larger outbreak.
The researchers attempted to mimic virus being deposited from an infected person onto everyday surfaces in a household or hospital setting, such as through coughing or touching objects.
They then investigated how long the virus remained infectious on these surfaces.
“If the viability of the two coronaviruses is similar, why is SARS-CoV-2 resulting in more cases? Emerging evidence suggests that people infected with SARS-CoV-2 might be spreading virus without recognizing, or prior to recognizing, symptoms,” they said.
“This would make disease control measures that were effective against SARS-CoV-1 less effective against its successor.”
In contrast to SARS-CoV-1, most secondary cases of virus transmission of SARS-CoV-2 appear to be occurring in community settings rather than healthcare settings.
However, healthcare settings are also vulnerable to the introduction and spread of SARS-CoV-2, and the stability of SARS-CoV-2 in aerosols and on surfaces likely contributes to transmission of the virus in healthcare settings.
The findings affirm the guidance from public health professionals to use precautions similar to those for influenza and other respiratory viruses to prevent the spread of SARS-CoV-2:
(i) avoid close contact with people who are sick;
(ii) avoid touching your eyes, nose, and mouth;
(iii) stay home when you are sick;
(iv) cover your cough or sneeze with a tissue, then throw the tissue in the trash;
(v) clean and disinfect frequently touched objects and surfaces using a regular household cleaning spray or wipe.
The team’s paper was published in the New England Journal of Medicine.
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Myndi G. Holbrook et al. Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1. New England Journal of Medicine, published online March 17, 2020; doi: 10.1056/NEJMc2004973
