The virus that causes COVID-19, coronavirus disease 2019, stays “live” for several hours in aerosols, and for days on surfaces, according to a new study in the New England Journal of Medicine (NEJM). These findings suggest that people may acquire the virus through the air and after touching contaminated objects.
The study, prepared by scientists from the National Institutes of Health, the Centers for Disease Control, UCLA, and Princeton University, was presented online by the journal on March 17. However, the study’s findings had been placed on a preprint server two weeks ago, so that they could be widely shared in the research community.
The study’s title, “Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1,” emphasizes that the study’s authors compared the stability of the novel coronavirus to that of the original SARS virus.
The scientists found that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was detectable in aerosols for up to three hours, up to four hours on copper, up to 24 hours on cardboard, and up to two to three days on plastic and stainless steel.
SARS-CoV-2, like its predecessor SARS-CoV-1, emerged from China. In 2002 and 2003, the original SARS infected more than 8,000. SARS-CoV-1 was eradicated by intensive contact tracing and case isolation measures, and no cases have been detected since 2004.
SARS-CoV-1 is the human coronavirus most closely related to SARS-CoV-2. In the stability study, the two viruses behaved similarly, which unfortunately fails to explain why COVID-19 has become a much larger outbreak. Still, the authors of the NEJM article suggested a couple of possibilities.
“We found that the stability of SARS-CoV-2 was similar to that of SARS-CoV-1 under the experimental circumstances tested,” the authors wrote. “This indicates that differences in the epidemiologic characteristics of these viruses probably arise from other factors, including high viral loads in the upper respiratory tract and the potential for persons infected with SARS-CoV-2 to shed and transmit the virus while asymptomatic.”
The NIH study 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. (For example, aerosols containing SARS-CoV-2 or SARS-CoV-1 were generated with the use of a three-jet Collison nebulizer and fed into a Goldberg drum to create an aerosolized environment.) The scientists then investigated how long the virus remained infectious on various surfaces.
The scientists highlighted additional observations from their study:
- Emerging evidence suggests that people infected with SARS-CoV-2 might be spreading virus without recognizing, or prior to recognizing, symptoms. 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:
- Avoid close contact with people who are sick.
- Avoid touching your eyes, nose, and mouth.
- Stay home when you are sick.
- Cover your cough or sneeze with a tissue, then throw the tissue in the trash.
- Clean and disinfect frequently touched objects and surfaces using a regular household cleaning spray or wipe.