Coronavirus
can persist in air for hours and on surfaces for days – study
Wednesday, 18
Mar 2020
(Reuters)
- The highly contagious novel coronavirus that has exploded into a global pandemic
can remain viable and infectious in droplets in the air for hours and on
surfaces up to days, according to a new study that should offer guidance to
help people avoid contracting the respiratory illness called COVID-19.
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 SARS-CoV-2 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 100.
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.
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 NIAID's 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.
As
part of their experiments, the researchers compared the stability of SARS-CoV-2
to that of SARS-CoV-1 under the same experimental circumstances and found
similar results. "This indicates that differences in the epidemiologic
characteristics of these viruses probably arise from other factors," they
conclude, "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.
.
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