Covid-19 found in air
samples up to 13 feet from patients
By AFP - April 11,
2020
WASHINGTON: A new study examining air samples
from hospital wards with Covid-19 patients has found the virus can travel up to
13 feet (four metres) – twice the distance current guidelines say people should
leave between themselves in public.
The preliminary results of the investigation by Chinese
researchers were published on Friday in Emerging Infectious Diseases, a journal
of the US Centers for Disease Control and Prevention (CDC).
They add to a growing debate on
how the disease is transmitted, with the scientists themselves cautioning that
the small quantities of virus they found at this distance are not necessarily
infectious.
The researchers, led by a team
at the Academy of Military Medical Sciences in Beijing, tested surface and air
samples from an intensive care unit and a general Covid-19 ward at Huoshenshan
Hospital in Wuhan. They housed a total of 24 patients between Feb 19 and March
2.
They found that the virus was
most heavily concentrated on the floors of the wards, “perhaps because of
gravity and air flow causing most virus droplets to float to the ground.”
High levels were also found on
frequently touched surfaces like computer mice, trashcans, bed rails and door
knobs.
“Furthermore, half of the
samples from the soles of the ICU medical staff shoes tested positive,” the
team wrote. “Therefore, the soles of medical staff shoes might function as
carriers.”
The team also looked at
so-called aerosol transmission – when the droplets of the virus are so fine
they become suspended and remain airborne for several hours, unlike cough or
sneeze droplets that fall to the ground within seconds.
They found that virus-laden
aerosols were mainly concentrated near and downstream from patients at up to 13
feet – though smaller quantities were found upstream, up to eight feet.
Encouragingly, no member of the
hospital staff was infected, “indicating that appropriate precautions could
effectively prevent infection,” the authors wrote.
They also offered advice that
bucks orthodox guidelines: “Our findings suggest that home isolation of persons
with suspected Covid-19 might not be a good control strategy” given the levels
of environmental contamination.
Aerosolisation of the
coronavirus is a contentious area for scientists who study it, because it is
not clear how infectious the disease is in the tiny quantities found in
ultrafine mist.
The World Health Organisation
has so far downplayed the risk.
US health authorities have
adopted a more cautious line and urged people to cover their faces when out in
public in case the virus can be transmitted through normal breathing and
speaking. - AFP
.
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