Washington, USA
The novel coronavirus can survive on some surfaces for days
or in the air for several hours, according to a US-government funded study
published on Tuesday.
Scientists found that
the virus that causes the Covid-19 disease had similar levels of viability outside
the body to its predecessor that caused SARS.
This means that other
factors like greater transmission between people with no symptoms might be why
the current pandemic is far greater than the SARS outbreak of 2002-2003.
The new paper was
published in the New England Journal of Medicine (NEJM) and carried out by
scientists from the Centres for Disease Control and Prevention (CDC),
University of California, Los Angeles and Princeton.
The new coronavirus was
detectable for up to four hours on copper and two to three days on plastic and
stainless steel, and for up to 24 hours on cardboard.
The team used a
nebulizer to simulate a person coughing or sneezing, and found that the virus
became an aerosol -- meaning its particles became suspended in the air --
making it detectable for almost three hours.
The study was first
posted on a medical pre-print website last week before it was peer-reviewed,
and attracted much attention, including some criticism from scientists who said
that it may have overstated the airborne threat.
The virus is
predominantly transmitted by respiratory droplets and in this form it is viable
for only a few seconds after a person coughs or sneezes.
Critics questioned
whether a nebulizer accurately mimicked a human cough or sneeze.
That said, there is
other evidence to suggest it can become an aerosol, albeit in rare
circumstances.
A Chinese paper that
was posted last week and is awaiting peer-review found an aerosolised form of
the new coronavirus was present in the bathrooms of patients in a Wuhan
hospital, as the virus is shed in stools.
An aerosolised form of
SARS was responsible for infecting hundreds of people in a Hong Kong apartment
complex in 2003, when a sewage line leaked on to a ceiling fan creating a
virus-laden plume.
The team behind the
NEJM study performed similar tests on the SARS virus, finding the two viruses
behave similarly.
But their similar
viability fails to explain why the novel coronavirus pandemic has infected
close to 200,000 people and caused almost 8,000 deaths, while the SARS epidemic
infected about 8,000 and killed nearly 800.
"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," wrote the researchers.
SARS-CoV-2 is the
technical name for the new coronavirus.
The findings affirm
guidance from public health professionals regarding social distancing, avoiding
touching the face, covering your cough or sneeze and frequently disinfecting
objects using cleaning sprays or wipes. - AFP
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