for “hot pot,” where utensils contaminated with saliva were
comingled in shared pots. This family included a 91-year-old
woman and a child who both tested positive for the virus
but did not display symptoms.”
Persistence of Coronaviruses and Environmental
Hygiene
One of the most unsettling aspects of coronaviruses is
its persistence on inanimate surfaces. Kampf, et al. (2020)
reviewed the literature on all available information about
the persistence of human and veterinary coronaviruses on
inanimate surfaces as well as inactivation strategies with
biocidal agents used for chemical disinfection in healthcare
facilities. The analysis of 22 studies reveals that human
coronaviruses such as SARS, MERS or endemic human
coronaviruses (HCoV) can persist on inanimate surfaces
like metal, glass or plastic for up to none days, but can
be efficiently inactivated by surface
disinfection procedures with 62 percent
to 71 percent ethanol, 0.5 percent
Although the viral hydrogen peroxide or 0.1 percent
load of coronaviruses sodium hypochlorite within 1 minute.
Other biocidal agents such as 0.05
on inanimate surfaces percent to 0.2 percent benzalkonium
is not known during chloride or 0.02 percent chlorhexidine
digluconate are less effective.
an outbreak situation
Kampf, et al. (2020) report that
it seem plausible ethanol (78 percent to 95 percent),
(70 percent to 100 per-
to reduce the viral 2-propanol
cent), the combination of 45 percent
load on surfaces by 2-propanol with 30 percent 1-propanol,
(0.5–2.5 percent),
disinfection, especially glutardialdehyde
formaldehyde (0.7–1 percent) and
of frequently touched povidone iodine (0.23–7.5 percent)
surfaces in the readily inactivated coronavirus infectiv-
ity by approximately 4 log10 or more.
immediate patient Sodium hypochlorite required a minimal
surrounding where concentration of at least 0.21 percent
to be effective. Hydrogen peroxide
the highest viral load was effective with a concentration of
can be expected.” 0.5 percent and an incubation time of
1 minute. As the researchers report,
“Data obtained with benzalkonium chloride at reasonable
contact times were conflicting. Within 10 minutes, a
concentration of 0.2 percent revealed no efficacy against
coronavirus whereas a concentration of 0.05 percent was
quite effective. 0.02 percent chlorhexidine digluconate was
basically ineffective.”
As Kampf, et al. (2020) explain, “Human coronaviruses
can remain infectious on inanimate surfaces at room
temperature for up to nine days. At a temperature of 30
degrees C or more the duration of persistence is shorter.
Contamination of frequent touch surfaces in healthcare
settings are therefore a potential source of viral transmis-
sion. Data on the transmissibility of coronaviruses from
contaminated surfaces to hands were not found. However,
it could be shown with influenza A virus that a contact of
5 seconds can transfer 31.6 percent of the viral load to the
hands. The transfer efficiency was lower (1.5 percent) with
parainfluenza virus 3 and a 5 second contact between the
surface and the hands.”
www.healthcarehygienemagazine.com • april 2020
The researchers add, “Although the viral load of coro-
naviruses on inanimate surfaces is not known during an
outbreak situation it seem plausible to reduce the viral load
on surfaces by disinfection, especially of frequently touched
surfaces in the immediate patient surrounding where the
highest viral load can be expected. The WHO recommends
‘to ensure that environmental cleaning and disinfection pro-
cedures are followed consistently and correctly. Thoroughly
cleaning environmental surfaces with water and detergent
and applying commonly used hospital-level disinfectants
(such as sodium hypochlorite) are effective and sufficient
procedures.’ The typical use of bleach is at a dilution of
1:100 of 5 percent sodium hypochlorite resulting in a final
concentration of 0.05 percent. Our summarized data with
coronaviruses suggest that a concentration of 0.1 percent
is effective in 1 minute. That is why it seems appropriate
to recommend a dilution 1:50 of standard bleach in the
coronavirus setting. For the disinfection of small surfaces
ethanol (62 percent to71 percent; carrier tests) revealed
a similar efficacy against coronavirus. A concentration of
70 percent ethanol is also recommended by the WHO for
disinfecting small surfaces.”
No data were found to describe the frequency of hands
becoming contaminated with coronavirus, or the viral load
on hands either, after patient contact or after touching
contaminated surfaces. As Kampf, et al. (2020) note, “The
WHO recommends to preferably apply alcohol-based hand
rubs for the decontamination of hands, e.g. after removing
gloves. Two WHO recommended formulations (based on
80 percent ethanol or 75 percent 2-propanol) have been
evaluated in suspension tests against SARS-CoV and MERS-
CoV, and both were described to be very effective. No in vitro
data were found on the efficacy of handwashing against
coronavirus contaminations on hands. In Taiwan, however,
it was described that installing hand wash stations in the
emergency department was the only infection control mea-
sure which was significantly associated with the protection
from healthcare workers from acquiring the SARS-CoV,
indicating that hand hygiene can have a protective effect.
Compliance with hand hygiene can be significantly higher
in an outbreak situation but is likely to remain an obstacle
especially among physicians. Transmission in healthcare
settings can be successfully prevented when appropriate
measures are consistently performed.”
Surfaces Matter in the Fight Against COVID-19
The virus that causes COVID-19 remains for several hours
to days on surfaces and in aerosols, a new study published
in The New England Journal of Medicine found.
The study suggests that people may acquire the coro-
navirus through the air and after touching contaminated
objects. Scientists discovered the virus is detectable for up
to three hours in aerosols, up to four hours on copper, up
to 24 hours on cardboard and up to two to three days on
plastic and stainless steel.
“This virus is quite transmissible through relatively casual
contact, making this pathogen very hard to contain,” said
James Lloyd-Smith, a co-author of the study and a UCLA
professor of ecology and evolutionary biology. “If you’re
touching items that someone else has recently handled, be
aware they could be contaminated and wash your hands.”
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