Scientists from the National Institute of Allergy and Infectious
Diseases (NIAID), part of the U.S. National Institutes of Health,
attempted to mimic the virus deposited from an infected person onto
everyday surfaces in a household or hospital setting, such as
through coughing or touching objects.
They used a device to dispense an aerosol that duplicated the
microscopic droplets created in a cough or a sneeze.
The scientists then investigated how long the virus remained
infectious on these surfaces, according to the study that appeared
online in the New England Journal of Medicine on Tuesday - a day in
which U.S. COVID-19 cases surged past 5,200 and deaths approached
The tests show that when the virus is carried by the droplets
released when someone coughs or sneezes, it remains viable, or able
to still infect people, in aerosols for at least three hours.
On plastic and stainless steel, viable virus could be detected after
three days. On cardboard, the virus was not viable after 24 hours.
On copper, it took 4 hours for the virus to become inactivated.
In terms of half-life, the research team found that it takes about
66 minutes for half the virus particles to lose function if they are
in an aerosol droplet.
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That means that after another hour and six minutes, three quarters
of the virus particles will be essentially inactivated but 25% will
still be viable.
The amount of viable virus at the end of the third hour will be down
to 12.5%, according to the research led by Neeltje van Doremalen of
the NIAIDís Montana facility at Rocky Mountain Laboratories.
On stainless steel, it takes 5 hours 38 minutes for half of the
virus particles to become inactive. On plastic, the half-life is 6
hours 49 minutes, researchers found.
On cardboard, the half-life was about three and a half hours, but
the researchers said there was a lot of variability in those results
"so we advise caution" interpreting that number.
The shortest survival time was on copper, where half the virus
became inactivated within 46 minutes.
(Reporting by Gene Emery; editing by Nancy Lapid, Caroline Humer and
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