Environ Int . Aerosol transmission of SARS-CoV-2? Evidence, prevention and control

[tetano]

Environ Int


. 2020 Aug 7;144:106039.
doi: 10.1016/j.envint.2020.106039. Online ahead of print.
Aerosol transmission of SARS-CoV-2? Evidence, prevention and control


Song Tang[SUP] 1 [/SUP], Yixin Mao[SUP] 2 [/SUP], Rachael M Jones[SUP] 3 [/SUP], Qiyue Tan[SUP] 2 [/SUP], John S Ji[SUP] 4 [/SUP], Na Li[SUP] 2 [/SUP], Jin Shen[SUP] 2 [/SUP], Yuebin Lv[SUP] 2 [/SUP], Lijun Pan[SUP] 2 [/SUP], Pei Ding[SUP] 2 [/SUP], Xiaochen Wang[SUP] 2 [/SUP], Youbin Wang[SUP] 2 [/SUP], C Raina MacIntyre[SUP] 5 [/SUP], Xiaoming Shi[SUP] 6 [/SUP]



Affiliations

• PMID: 32822927
• DOI: 10.1016/j.envint.2020.106039

Abstract

As public health teams respond to the pandemic of coronavirus disease 2019 (COVID-19), containment and understanding of the modes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission is of utmost importance for policy making. During this time, governmental agencies have been instructing the community on handwashing and physical distancing measures. However, there is no agreement on the role of aerosol transmission for SARS-CoV-2. To this end, we aimed to review the evidence of aerosol transmission of SARS-CoV-2. Several studies support that aerosol transmission of SARS-CoV-2 is plausible, and the plausibility score (weight of combined evidence) is 8 out of 9. Precautionary control strategies should consider aerosol transmission for effective mitigation of SARS-CoV-2.

Keywords: Airborne transmission; COVID-19; Hospital; Mask; Precaution; Respiratory protection.

 

[sharon sanders]

Posted with permission

@jwgale

Coronavirus in Vacant Apartment Suggests Toilets’ Role in Spread
2020-08-26 13:40:51.808 GMT


By Jason Gale
(Bloomberg) -- The discovery of coronavirus in the bathroom
of an unoccupied apartment in Guangzhou, China, suggests the
airborne pathogen may have wafted upwards through drain pipes,
an echo of a large SARS outbreak in Hong Kong 17 years ago.
Traces of SARS-CoV-2 were detected in February on the sink,
faucet and shower handle of a long-vacant apartment, researchers
at the Chinese Center for Disease Control and Prevention said in
a study published this month in Environment International. The
contaminated bathroom was directly above the home of five people
confirmed a week earlier to have Covid-19.
The scientists conducted “an on-site tracer simulation
experiment” to see whether the virus could be spread through
waste pipes via tiny airborne particles that can be created by
the force of a toilet flush. They found such particles, called
aerosols, in bathrooms 10 and 12 levels above the Covid-19
cases. Two cases were confirmed on each of those floors in early
February, raising concern that SARS-CoV-2-laden particles from
stool had drifted into their homes via plumbing.
Read More: Coronavirus Lurking in Feces May Reveal Hidden
Risk of Spread
The new report is reminiscent of a case at Hong Kong’s Amoy
Gardens private housing estate almost two decades ago, when 329
residents caught severe acute respiratory syndrome, or SARS, in
part because of faulty sewage pipelines. Forty-two residents
died, making it the most devastating community outbreak of SARS,
which is also caused by a coronavirus.
“Although transmission via the shared elevator cannot be
excluded, this event is consistent with the findings of the Amoy
Gardens SARS outbreak in Hong Kong in 2003,” Song Tang, a
scientist with the China CDC Key Laboratory of Environment and
Population Health, and colleagues wrote in the study, which
cited unpublished data from China CDC.
Apartments in multistory buildings may be linked via a
shared wastewater system, said Lidia Morawska, director of the
International Laboratory for Air Quality and Health at
Australia’s Queensland University of Technology. While solids
and liquids descend the network, sewer gases -- often detectable
by their odor -- sometimes rise through pipes, said Morawska,
who wasn’t part of the research team.
“If there’s smell, it means that somehow air has been
transported to where it shouldn’t go,” Morawska said in an
interview.

Respiratory Droplets

SARS-CoV-2 spreads mainly through respiratory droplets --
spatters of saliva or discharge from the nose, according to the
World Health Organization. Since the first weeks of the
pandemic, however, scientists in China have said infectious
SARS-CoV-2 virus in the stool of Covid-19 patients may also play
a role in transmission. A February study of 73 patients
hospitalized with the coronavirus in Guangdong province found
more than half tested positive for the virus in their stool.
How Do People Catch Covid-19? Here’s What Experts Say:
QuickTake
Previous research has shown that toilet flushes can
generate germ-laden aerosols from the excreta, the China CDC
scientists said. Those particles can remain in the air for long
periods and be dispersed over distances of more than 1 meter (3
feet), particularly in confined, poorly ventilated spaces.
Fecal aerosolization occurred with SARS, and it’s possible
that it may rarely occur with SARS-CoV-2, depending on sewage
systems, said Malik Peiris, chair of virology at the University
of Hong Kong’s School of Public Health. The China CDC study
found traces of virus, “which is not the same thing as
infectious virus,” he said. “But one has to keep the possibility
in mind.”

Fecal Plume

In the Amoy Gardens case, warm, moist air from the bathroom
of a SARS patient excreting “extremely high concentrations” of
virus in feces and urine established a plume in an air shaft
that spread the airborne virus to other apartments, research
showed.
Although toilets are a daily necessity, they “may promote
fecal-derived aerosol transmission if used improperly,
particularly in hospitals,” the China CDC researchers said. They
cited a fluid-dynamics simulation that showed a “massive upward
transport of virus aerosol particles” during flushing, leading
to large-scale virus spread indoors.
“The study finds high plausibility for airborne
transmission and outlines the evidence in great detail,” said
Raina MacIntyre, professor of global biosecurity at the
University of New South Wales in Sydney, who was part of an
international team invited to collaborate with China CDC on the
study.
Previous investigations confirmed that SARS-CoV-2 genetic
material was found on toilets used by Covid-19 patients, in the
air in hospital nurses’ stations, on air outlet vents, and
multiple other sites. The extent to which fecal aerosol plumes
are infecting people with the SARS-CoV-2 virus isn’t known, said
Queensland’s Morawska.
“There are lots of situations where things happen and are
pretty unusual,” said Morawska, who was part of a team that
investigated the Amoy Gardens contagion. Scientists should
investigate the “unusual situations” because, by understanding
them, they may find “they’re not that unusual.”

To contact the reporter on this story:
Jason Gale in Melbourne at j.gale@bloomberg.net
To contact the editors responsible for this story:
Michael Patterson at mpatterson10@bloomberg.net
Jason Gale, John Lauerman