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Contamination by respiratory viruses on outer surface of medical masks used by hospital healthcare workers

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Background Medical masks are commonly used in health care settings to protect healthcare workers (HCWs) from respiratory and other infections. Airborne respiratory pathogens may settle on the surface of used masks layers, resulting in contamination. The main aim of this study was to study the presence of viruses on the surface of medical masks. Methods Two pilot studies in laboratory and clinical settings were carried out to determine the areas of masks likely to contain maximum viral particles. A laboratory study using a mannequin and fluorescent spray showed maximum particles concentrated on upper right, middle and left sections of the medical masks. These findings were confirmed through a small clinical study. The main study was then conducted in high-risk wards of three selected hospitals in Beijing China. Participants (n = 148) were asked to wear medical masks for a shift (6–8 h) or as long as they could tolerate. Used samples of medical masks were tested for presence of respiratory viruses in upper sections of the medical masks, in line with the pilot studies. Results Overall virus positivity rate was 10.1% (15/148). Commonly isolated viruses from masks samples were adenovirus (n = 7), bocavirus (n = 2), respiratory syncytial virus (n = 2) and influenza virus (n = 2). Virus positivity was significantly higher in masks samples worn for > 6 h (14.1%, 14/99 versus 1.2%, 1/49, OR 7.9, 95% CI 1.01–61.99) and in samples used by participants who examined > 25 patients per day (16.9%, 12/71 versus 3.9%, 3/77, OR 5.02, 95% CI 1.35–18.60). Most of the participants (83.8%, 124/148) reported at least one problem associated with mask use. Commonly reported problems were pressure on face (16.9%, 25/148), breathing difficulty (12.2%, 18/148), discomfort (9.5% 14/148), trouble communicating with the patient (7.4%, 11/148) and headache (6.1%, 9/148). Conclusion Respiratory pathogens on the outer surface of the used medical masks may result in self-contamination. The risk is higher with longer duration of mask use (> 6 h) and with higher rates of clinical contact. Protocols on duration of mask use should specify a maximum time of continuous use, and should consider guidance in high contact settings. Viruses were isolated from the upper sections of around 10% samples, but other sections of masks may also be contaminated. HCWs should be aware of these risks in order to protect themselves and people around them.
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R E S E A R C H A R T I C L E Open Access
Contamination by respiratory viruses on
outer surface of medical masks used by
hospital healthcare workers
Abrar Ahmad Chughtai
1*
, Sacha Stelzer-Braid
2
, William Rawlinson
3
, Giulietta Pontivivo
4
, Quanyi Wang
5
, Yang Pan
5
,
Daitao Zhang
5
, Yi Zhang
5
, Lili Li
6
and C. Raina MacIntyre
7,8
Abstract
Background: Medical masks are commonly used in health care settings to protect healthcare workers (HCWs) from
respiratory and other infections. Airborne respiratory pathogens may settle on the surface of used masks layers,
resulting in contamination. The main aim of this study was to study the presence of viruses on the surface of
medical masks.
Methods: Two pilot studies in laboratory and clinical settings were carried out to determine the areas of masks
likely to contain maximum viral particles. A laboratory study using a mannequin and fluorescent spray showed
maximum particles concentrated on upper right, middle and left sections of the medical masks. These findings
were confirmed through a small clinical study. The main study was then conducted in high-risk wards of three
selected hospitals in Beijing China. Participants (n= 148) were asked to wear medical masks for a shift (68h)oras
long as they could tolerate. Used samples of medical masks were tested for presence of respiratory viruses in upper
sections of the medical masks, in line with the pilot studies.
Results: Overall virus positivity rate was 10.1% (15/148). Commonly isolated viruses from masks samples were
adenovirus (n= 7), bocavirus (n= 2), respiratory syncytial virus (n = 2) and influenza virus (n = 2). Virus positivity was
significantly higher in masks samples worn for > 6 h (14.1%, 14/99 versus 1.2%, 1/49, OR 7.9, 95% CI 1.0161.99) and
in samples used by participants who examined > 25 patients per day (16.9%, 12/71 versus 3.9%, 3/77, OR 5.02, 95%
CI 1.3518.60). Most of the participants (83.8%, 124/148) reported at least one problem associated with mask use.
Commonly reported problems were pressure on face (16.9%, 25/148), breathing difficulty (12.2%, 18/148),
discomfort (9.5% 14/148), trouble communicating with the patient (7.4%, 11/148) and headache (6.1%, 9/148).
Conclusion: Respiratory pathogens on the outer surface of the used medical masks may result in self-
contamination. The risk is higher with longer duration of mask use (> 6 h) and with higher rates of clinical contact.
Protocols on duration of mask use should specify a maximum time of continuous use, and should consider
guidance in high contact settings. Viruses were isolated from the upper sections of around 10% samples, but other
sections of masks may also be contaminated. HCWs should be aware of these risks in order to protect themselves
and people around them.
Keywords: Mask, Health care workers, Viruses, Infection control
© The Author(s). 2019 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and
reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver
(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
* Correspondence: abrar.chughtai@unsw.edu.au
1
School of Public Health and Community Medicine, UNSW Medicine,
University of New South Wales, Level 2, Samuels Building, Sydney 2052,
Australia
Full list of author information is available at the end of the article
Chughtai et al. BMC Infectious Diseases (2019) 19:491
https://doi.org/10.1186/s12879-019-4109-x
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Background
Infectious diseases are a continuing threat, with constant
emergence or re-emergence of serious diseases in vari-
ous parts of the world and healthcare workers (HCWs)
are particularly at-risk of exposure to index cases [14].
Various types of personal protective equipment (PPE)
are recommended and used by HCWs to protect from
infections, including medical masks, respirators, gloves,
gowns, goggles and face shield [5,6]. In healthcare set-
tings, medical masks are used by HCWs to protect from
splashes and sprays of blood and body fluids, and by sick
individuals to prevent spread of respiratory infections to
others [7]. Reuse and extended use of masks are also
common in many parts of the world, particularly during
outbreaks and pandemics [8,9]. Respiratory pathogens
may be present on used masks layers and lead to infec-
tion of the wearer [10]. In hospital settings, these patho-
gens may be generated from breathing, coughing or
sneezing patients or during aerosol generating medical
procedures [11]. Studies have shown that influenza virus
can remain airborne for 3 h after a patient has passed
through an emergency department [12]. While using
masks, or during long periods of time of re-using them,
these pathogens may cause infection through hand or
skin contamination, ingestion, or mucus membrane con-
tact [10].
Currently there are limited data on the presence of re-
spiratory pathogens on surface of PPE and other fomites
in hospital settings. Previous studies show that influenza
and respiratory syncytial virus (RSV) may survive on
outer surface of PPE [1114]. A study showed that
influenza viruses may survive on hard surfaces for
2448 h, on cloth up to 812 h and on hands for up
to 5 min [13]. A previous study in an Australian Neo-
natal Intensive Care Unit (NICU), respiratory syncyt-
ial virus (RSV) RNA was identified from 4% of dress
samples and 9% of environmental samples [14]. If
health departments do not provide clear guidance on
the use of masks in these situations, HCWs may con-
tinue using contaminated masks and may get infec-
tion [15]. The risk of self-contamination of HCWs is
influenced by the mask itself, its shape and proper-
ties, and the virus concentration on its surface. To
our knowledge, only one study examined the presence
of contamination on mask and various bacteria were
isolated from outer surface of medical masks [16].
The main aim of this study was to study the level of
contamination on the surface of medical masks.
Methods
Pilot studies
Medical masks were tested as per protocols developed
through two pilot studies in Sydney Australia.
Pilot study 1 (laboratory testing)
The aim of this pilot study was to identify areas of max-
imum virus concentration on the surface of masks. Med-
ical masks were donned on a simple mannequin in a
laboratory setting and fluorescent particles (UV Glow
powder) were sprayed front on and side on from a dis-
tance of approximately 1 m using a spray bottle. We per-
formed three experiments from the front and three
experiments from the sides of mannequin. UV light
wasusedtoquantifythedensityofparticlesonmask
surface and to identify area of maximum concentra-
tion. In all three experiments, most particles were
concentrated on upper right, middle and left sections
of the masks (Figs. 1and 2).
Pilot study 2 (clinical testing)
The second pilot study was conducted in two tertiary re-
ferral hospitals in Sydney Australia to develop testing
methodology. Twelve HCWs (doctors and nurses) from
the infectious diseases, respiratory/ chest wards and in-
tensive care unit (ICU) participated in the study. HCWs
were asked to wear medical masks for a shift (minimum
30 min) used masks were tested in the Virology Research
Laboratory, University of New South Wales and
Prince of Wales Hospital Sydney Australia. If a respir-
ator was indicated due to airborne inflictions, HCWs
were excluded from the study and were allowed to
use a respirator.
Medical masks were divided into six sections as shown
in Fig. 3. Samples were taken from upper three sections
of masks i.e. 36 samples were tested in total (12 masks X
3 samples). The outer layer of the mask was removed
using sterile tweezers. The mask layer was placed into a
15 ml falcon tube containing 700 μl of Phosphate buff-
ered saline and vortexed for 20 s. After 10 min incuba-
tion the mask was placed in a custom made filter tube
inside an eppendorf tube and centrifuged briefly. The fil-
trate was then transferred to 1.5 ml Eppendorf tube.
Total nucleic acid was extracted on the Kingfisher Flex
(Thermo Scientific) using the MagNA Pure Total Nu-
cleic Acid Isolation Kit (Roche) according to the manu-
facturers instructions. Presence of respiratory viruses
was detected using the Seegene AllplexRespiratory
Panel Assays 1,2,3 (Seegene).
Main study
The main study was conducted in respiratory wards and
fever clinics of three selected hospitals in Beijing China
from December 2017 to January 2018. Doctors and
nurses from selected wards were invited to participate in
the study. Participants include nursing and medical staff
aged > 18 years working full time in the ward who were
able to provide written and informed consent. Partici-
pants with pre-existing respiratory, medical illness or
Chughtai et al. BMC Infectious Diseases (2019) 19:491 Page 2 of 8
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pregnancy were excluded. As we did not test the partici-
pants, detail history on respiratory symptoms was taken
to rule out contamination of masks by participants
themselves.
HCWs from the participating wards were asked to
wear medical masks for a shift (68 h), or as long as they
could tolerate the masks with no adverse event. Three
layered standard medical masks were used. If HCWs
used more than one mask during their shift, first sample
was collected and tested. Used medical masks were col-
lected at the end of the day and were stored immediately
in zip-lock bags. HCWs were advised to store masks in
in zip-lock bags while they take off the masks during
break time. All masks samples were labelled with partici-
pantsID and hospital ID. At the end of the study,
HCWs were asked to complete a short survey to collect
information on mask use in routine (type of mask used,
number of masks used and situations when masks were
normally used) and during the study period (wearing
time, number of patients seen, situations when masks
were used, aerosol generating procedures performed and
hand hygiene during donning and doffing). Partici-
pants reported number of masks usedand number
of patients seenin absolute numbers. Duration of
mask usewas recorded in hours as, < 1 h, 1 to 2 h, 2
to 4 h, 5 to 6 h, 7 to 8 h, > 8 h. Situations when
masks were usedwere categorized into: used con-
tinuously,used continuously except during breaks,
used only during patientsencountersand used
only high-risk patient encounters.
Mask testing for the main study
Medical masks were tested in the Beijing CDC laboratory.
All masks were collected immediately after use in zip-lock
bags and kept at 80 °C until testing. Pilot studies showed
that upper sections of masks were more contaminated (Figs.
1and 2). The outer layers of upper right, middle and left
mask were separated with a same size, placed into separated
tubes containing 700 μl PBS buffer (Gibco, USA), vortexed
for 1 min, and finally aliquoted 50 μlforviraltesting.We
performed three tests on upper right, middle and upper left
sections of the masks on around a quarter mask sample
(26%) and performed one test on the remaining mask sam-
ples (74%). For one testing, outer layers of upper right, mid-
dle and left section of mask were separated and placed into
the same tube. Viral DNA/RNA was extracted using King-
Fisher Flex 96 viral DNA/RNA purification kit (Thermo
Fisher, USA) according to the manufacturersinstructions.
The reverse-transcription polymerase chain reaction was per-
formed to amplify 15 viral target genes, including influenza
A/B virus, influenza A(H1N1) and A(H3N2), parainfluenza
viruses 14, rhinoviruses, bocavirus, human metapneumo-
virus, adenovirus, respiratory syncytial virus, coronaviruses
OC43, 229E, NL63 and HKU1 using a commercial multiplex
combined real-time PCR detection kit for Respiratory virus,
which is developed by Jiangsu Uninovo Biological Technol-
ogy Co. Ltd.in China.
Sample size
Currently there is very limited data on testing of masks
surface for presence of pathogens. In previous studies
Fig. 1 Fluorescent particles (UV Glow power) following spraying from 1 m from the front of the mask
Fig. 2 Fluorescent particles (UV Glow powder) following spraying from 1 m from the side of the mask
Chughtai et al. BMC Infectious Diseases (2019) 19:491 Page 3 of 8
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
influenza virus was detected on over 50% of the fomites
tested in community settings during influenza season
[17]. The rate is expected to be higher in the healthcare
setting and moreover other viruses will also be tested.
Assuming 25% higher positivity rate in the healthcare
setting, the required sample size would be 134 masks,
with 80% power and two-sided 5% significance level for
detecting a significant difference. Some HCWs might
not be able to provide mask samples, we aimed to re-
cruited 145 HCWs in total for this study.
Analysis
Descriptive analysis was conducted, and rates and fre-
quencies were calculated. Univariate analysis was per-
formed to identify the factors associated with mask
positivity. Logistic regression was used to calculate odds
ratio (OR) and 95% confidence intervals (CI) Data were
analyzed in SAS (SAS Institute Inc., USA) version 9.4.
Ethics and consent to participate
Ethics approval for pilot study was sought from South
Eastern Sydney Local Health District (SESLHD). Eth-
ics approval for the main study was sought from Hu-
man Research Ethics Committee UNSW (HC16703)
and IBR China. Written consent as obtained from all
participants.
Results
Of 36 samples in pilot testing, three samples were posi-
tive for human enterovirus. Two samples were positive
from outer sections of mask, while one sample was posi-
tive from middle section. No other viruses were detected
in mask samples.
A total of 158 participants were recruited from three
hospitals in the main study. Ten participants provided
more than one samples for the testing, so we excluded
these cases from analysis due to uncertainty around the
duration of mask use being tested. Most participants
were recruited from Hospital A (52%, 77/148), largely
from the respiratory ward 47.3%, 70/148). Around half
of the participants were doctors (45.9%, 68/148), and
majority were female (81.8%, 121/148). In routine clin-
ical practice, almost all participants (98.6%, 146/148) had
previously used disposable medical masks. Generally,
most of the participants had been using 1 or 2 medical
masks per day (90.6%, 134/148) and around two third
participant (68.2%, 101/148) had been using mask all the
time during the clinical work (Table 1).
During the study period, around 2/3 participants used
masks for > 6 h –“78h80 participants (54.1%) and >8
h19 participants (12.8%). The remaining 1/3 used masks
for 6h –“12h1 participant (0.7%), 34h8 partici-
pants (5.4%) and 56h40 participants (27%). Most par-
ticipants (78.4%, 116/148) used masks either continuously
or continuously except breaks. The majority of partici-
pants (83.8%,124/148) reported at least one problem
Fig. 3 Sections of medical masks for testing
Table 1 Demographic data
Variables Number (n= 148) Percent
Hospital
Hospital A 77 52.0
Hospital B 26 17.6
Hospital C 45 30.4
Ward
Internal medicine 52 35.1
Respiratory 70 47.3
Pediatrics 26 17.6
Position
Doctor 68 45.9
Nurse 80 54.1
Age
30 year 41 27.7
3140 years 68 45.9
41 years 39 26.4
Gender
Male 27 18.2
Female 121 81.8
Type of mask normally used in the hospital
Cloth re-usable facial masks 2 1.4
Disposable medical masks 146 98.6
Number of masks routinely used in the hospital
1 46 31.1
2 88 59.5
3 10 6.8
4 4 2.7
When masks are normally used
All the time 101 68.2
When treating certain patients 47 32.8
Chughtai et al. BMC Infectious Diseases (2019) 19:491 Page 4 of 8
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associated with masks use. Commonly reported problems
were pressure on face (16.9%, 25/148), breathing difficulty
(12.2%, 18/148), discomfort (9.5% 14/148), trouble com-
municating with the patient (7.4%, 11/148) and headache
(6.1%, 9/148). Majority of participants washed their hand
during donning (91.2%, 135/148) /doffing (88.5%, 131/
148) of medical masks and before (74.3%, 110/148) /after
(85.1%, 126/148) touching patients. During the study
period, 68% (101/148) participants used other PPE as well
mostly gloves and hair covers.
Overall virus positivity rate was 10.1% (15/148) and
rates were similar after 1 testing on mask (10%, 11/110)
compared to three testing (10.5%, 4 /38) (OR 1.06, 95%
CI 0.323.55). Adenovirus was most commonly isolated
from the masks (n= 7), followed by bocavirus (n= 2),
RSV (n = 2) and influenza virus (n = 2) (Table 2).
Compared to the participants working in internal
medicine department, virus positivity rates were lower
among those working in respiratory (OR 0.04, 95% CI
0.010.34) and pediatric (OR 0.12, 95% CI 0.010.97)
departments. Virus positivity was significantly higher on
masks samples worn by participants who used masks for
> 6 h, compared to those who used mask for 6 h that
day (OR 7.9, 95% CI 1.0161.99). Similarly, virus positiv-
ity was significantly higher on masks samples worn by
participants who examined > 25 patients per day, com-
pared to who examined 25 patients (OR 5.02, 95% CI
1.3518.60). Virus positivity rates were also higher in
mask samples collected from males, participants who
used mask during encounters with high risk patients and
those who performed aerosol generating procedures
(AGPs), however the difference was not statistically sig-
nificant (Table 3).
Discussion
To our knowledge this is the first study examining the
presence of respiratory viruses on the outer surface of
used medical masks. One in ten masks were positive for
any virus which highlights the risk of self-contamination
to the wearer, particularly on doffing [18]. Reuse and ex-
tended use of masks are very common, particularly in
low income countries and during outbreaks and pandemics
when supplies are short, and demand is high [19,20]. Staff
should be aware of the risk associated with the reuse and
extended use of masks and respiratory protective devices
and high clinical contact. Large scale studies should be con-
ducted to determine the contamination on other PPEs as
well and to quantify the risk of infection among HCWs.
Epidemics of a new infectious disease may be devastat-
ing due to global spread, disease burden and high case
fatality. PPE are generally considered lowest among in-
fection control hierarchy and recommended to be used
with other administrative and environmental control
measures [21]. However, masks, respirators and other
PPE are important during initial phase of outbreak and
pandemic when drugs and vaccine are not available [22].
PPE can easily get contaminated during clinical care of
sick patients which may result in an increased risk of in-
fection in wearer [18]. Many simulation studies have also
shown presence of particles on the potential surface of
PPE and associated risk of self-contamination during
doffing of PPE [5,2224]. In this study we only tested
the presence of viruses on the medical masks. Overall
virus positivity rate in this was 10.1% (15/148) and
adenovirus was isolated from 7 mask samples while
bocavirus, RSV and influenza viruses were isolated from
2 samples each. Prospero et al. conducted a study in
dental settings and estimated the bacterial contamin-
ation on surface of masks used by dentist, lamps, areas
near spittoons, and mobile trays. Sterile nitrocellulose
filters were applied on these surfaces to isolate patho-
gens. Highest levels of bacterial contamination
(Streptococcus species 42%, Staphylococcus species
41%, and gram-negative bacteria 17%) were recorded
on the external surface of masks wore by dentist [16].
Large scale studies should be conducted to examine
presence of various pathogens on the surface of masks
and other PPE.
In this study, the risk of mask contamination was asso-
ciated with duration of masks use and number of pa-
tients seen. Currently there is no standard duration for
the time period that facemasks and respirators can safely
Table 2 Pathogens isolated from outer surface of masks
Viruses Positive in one test (Total tests 110) Positive in three tests & sample location (Total test 38)
Adenovirus
a
6 1 middle section of mask
Bocavirus
a
20
Human metapneumovirus
a
0 1 right section of mask
Influenza B & type 4 parainfluenza virus
b
10
Influenza H1N1 & influenza B
c
10
Respiratory syncytial virus
a
1 1 middle section of mask
Type 2 parainfluenza virus
a
0 1 right section of mask
Total positive (Positivity rate) 11 (9.4%) 4 (9.8%)
a
Isolated from internal medicine ward,
b
isolated from pediatric ward
c
isolated from respiratory ward
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be used. Theoretically, there may be a risk of infection
in wearer if contaminated masks are used for prolonged
time. Currently there are no data around risk associated
with reuse and extended used of masks and other PPE.
One study showed that influenza virus may survive on
mask surface and maintained infectivity for at least 8 h
[25]. Our study showed very low infection among HCWs
who used masks for 6 h. High virus positivity on masks
samples worn by HCWs who examined > 25 patients,
may be due to more frequent clinical contact with in-
fective cases and transfer of more pathogens from pa-
tients to mask surface. Virus positivity rates were also
higher in those working in internal medicine department
compared to respiratory and pediatric departments. The
reason of high virus positivity in internal medicine de-
partment is not clear, but this may be due to using
Table 3 Factors associated with virus positivity on masks surface
Variables Positive for any virus Odds ratio (OR) (95% CI)
Number Percent
Hospital
Hospital A 12/77 15.6 Ref
a
Hospital B 1/26 3.8 0.22 (0.031.75)
Hospital C 2/45 4.4 0.25 (0.051.18)
Ward
Internal medicine department 13/52 25 Ref
Respiratory department 1/70 1.4 0.04 (0.010.34)
d
Pediatrics department 1/26 3.8 0.12 (0.010.97)
d
Gender
Male 4/27 14.8 Ref
Female 11/121 9.1 0.57 (0.161.97)
Position
Doctor 7/68 10.3 Ref
Nurse 8/80 10 0.97 (0.332.82)
Age
30 years 5/41 12.2 Ref
3140 years 5/68 7.4 0.57 (0.152.11)
41 years 5/39 12.8 1.06 (0.283.98)
Mask use time during the study
6 h 1/49 2 Ref
> 6 h 14/99 14.1 7.9 (1.0161.99)
d
Patientsseen
25 cases 3/77 3.9 Ref
> 25 cases 12/71 16.9 5.02 (1.3518.60)
d
How medical masks were used
Used continuously 4/28 14.3 Ref
Used continuously except breaks
b
9/88 10.2 0.65 (0.192.22)
Used only during patients encounters 0/26 0 0.10 (0.012.12)
Used only high-risk patient encounters 2/6 33.3 3.02 (0.4321.44)
Preformed AGPs
c
during the study
No 7/95 7.4 Ref
Yes 8/53 15.1 2.24 (0.766.55)
Hand wash
No 2/13 15.4 Ref
Yes 13/135 9.6 0.59 (0.122.94)
a
Reference
b
lunch, tea and toilet
c
aerosol generating procedures
d
Significant results
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varying infection control policies and practices. High risk
perception and more infection control measures may re-
sult in low virus positivity in in respiratory and pediatric
departments. However, the sample sizes and number of
positive results were too low to make meaningful com-
parisons between departments. There is a need for more
research to define the exact threshold of safe duration,
and to develop a comprehensive policy on the use of
masks in hospital settings and protocols should specify a
maximum time of continuous use and should consider
guidance in high contact settings.
We also aimed to identify the area on the mask surface
with maximum respiratory virus concentration. Labora-
tory based pilot study showed maximum fluorescent
contamination on upper sections of the masks, which is
also the likely area to be touched on removal. Of the
three positive tests in hospital-based pilot study, two
samples were positive from outer sections of mask, while
one sample was positive from middle section. In the
main study we were able to check the location of con-
tamination on a quarter of mask samples. Of the 38
mask samples, one or more viruses were isolated from
four (10.5%) samples two from middle section of
masks and two from right section of the masks. This
presents a large area of potential contamination which
place HCW at risk when removing a mask. These data
may assist in developing policies on for doffing of masks
after encounter with infective cases. As a general rule,
HCWs should not reuse masks, should restrict use to
less than 6 h and avoid touching the outer surface of
mask during doffing, and practice hand hygiene after
removal.
There are limitations of this study. Due to funding
constraints we tested selected masks samples. We per-
formed three tests on a sub-sample (26%) to identify the
area of maximum concentration. Moreover, we just
tested upper three sections of medical masks based on
the first pilot study, while lower three sections should
also be tested. Then we tested only outer layer of masks
and did not check filtering layer and inner layer due to
funding constraints. Ideally all sections and layers of
masks should be tested. We collected detail history from
the participants to rule out any existing respiratory ill-
ness. Although none of the participant had a respiratory
or a medical illness, it is not possible to determine
whether viruses isolated from the masks surface were
from exogenous or endogenous source. For example,
adenovirus was most commonly identified in this study
and is associated with mild or no respiratory illnesses.
Ideally participants should also be swabbed to rule out
infections, and the inside surface should also be tested.
However, given the large variations of infection probabil-
ity in different types of wards, it is unlikely that all vi-
ruses came from the background infection. To overcome
this limitation, detailed history on respiratory symptoms
was taken to rule out contamination of masks by clinic-
ally ill participants themselves. Moreover, we only exam-
ined viruses on the masks, while bacteria and other
pathogens may also be present [16]. Mask use was not
monitored, and self-reported compliance was recorded.
Previous studies show that self-reported compliance is
generally reported to be higher compared to the actual
compliance [26,27]. We also did not document the
method of mask removal, nor the number of times the
HCW touched the mask.
Conclusion
To maintain the functionality and capacity of the health
care workforce during outbreaks or pandemics of emer-
ging infections, HCWs need to be protected. This study
provides new data, which will help developing policies
for safe workplace environment. The study shows that
the prolonged use of medical masks (> 6 h) and frequent
clinical contact in healthcare setting increase the risk to
health workers through contaminated PPE. Protocols on
duration of mask use should specify a maximum time of
continuous use.
Abbreviations
AGPs: Aerosol generating procedures; HCW: Healthcare workers;
ICU: Intensive care unit; NICU: Neonatal Intensive Care Unit; PPE: Personal
protective equipment; RSV: Respiratory syncytial virus; SESLHD: South Sydney
Local Health District
Acknowledgements
Thanks to the staff at the Beijing Centre for Diseases Prevention and Control
and hospitals staff for participating in the study. We would like to thank Xin
Chen (UNSW), Yimeng Liu (Beijing Center for Diseases Prevention and
Control) and Jiachen Zhao, Beijing Center for Diseases Prevention and
Control, for assisting with sample collection and handling. Thanks to A/Prof
Euan Tovey (Woolcock Institute for Medical Research) for supply of
mannequins.
Authorscontributions
AAC - Conception and design of study, data analysis and manuscript writing.
SSB, WR, GP Data/ sample collection and lab testing for pilot studies in
Australia, manuscript review. QW, YP, YZ and LL Data/ sample collection for
the main study in China, manuscript review. DZ - Testing for the main study
in China, manuscript review. CRM - Contributed to study design and
manuscript writing. All authors approved the study.
Funding
This study was supported by NHMRC Centre for Research Excellence Grant
APP1107393 (Integrated Systems for Epidemic Response [ISER]). Funding
body has no role in design of the study and collection, analysis, and
interpretation of data and in writing the manuscript.
Availability of data and materials
The datasets used and/or analysed during the current study are available
from the corresponding author on reasonable request.
Ethics approval and consent to participate
Ethics approval for pilot study was sought from Eastern Sydney Local Health
District (SESLHD). Ethics approval for the main study was sought from
Human Research Ethics Committee UNSW (HC16703) and IBR China. Consent
was obtained from all participants before recruitment.
Chughtai et al. BMC Infectious Diseases (2019) 19:491 Page 7 of 8
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
Consent for publication
Not applicable .
Competing interests
All authors have completed the Unified Competing Interests form (available
on request from the corresponding author) and declare that: AAC had
testing of filtration of masks by 3 M for PhD. CRM has held an Australian
Research Council Linkage Grant with 3 M as the industry partner, for
investigator driven research. 3 M have also contributed supplies of masks
and respirators for investigator-driven clinical trials. She has received research
grants and laboratory testing as in-kind support from Pfizer, GSK and Bio-CSL
for investigator-driven research. The remaining authors declare that they
have no competing interests and have no non-financial interests that may
be relevant to the submitted work.
Author details
1
School of Public Health and Community Medicine, UNSW Medicine,
University of New South Wales, Level 2, Samuels Building, Sydney 2052,
Australia.
2
University of New South Wales, Virology Research Laboratory,
Prince of Wales Hospital, Randwick, NSW 2031, Australia.
3
SAViD (Serology &
Virology Division), Prince of Wales Hospital, Randwick, Australia.
4
Infection
Prevention Management and Staff Health Services- St Vincents Hospital,
Sydney, Australia.
5
Beijing Center for Diseases Prevention and Control,
Beijing, China.
6
Fangshan Center for Diseases Prevention and Control, Beijing,
China.
7
Biosecurity Program, The Kirby Institute, University of New South
Wales, Sydney, NSW 2052, Australia.
8
College of Public Service & Community
Solutions, and College of Health Solutions, Arizona State University, Phoenix,
AZ 85004, USA.
Received: 28 January 2019 Accepted: 20 May 2019
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Background: Masks are often worn in healthcare settings to prevent the spread of infection from healthcare workers (HCWs) to patients. Masks are also used to protect the employee from patient-generated infectious organisms but poor compliance can reduce efficacy. The aim of this study was to examine the factors influencing compliance with the use of medical and cloth masks amongst hospital HCWs. Methods: HCWs compliance with the use of medical and cloth masks was measured over a 4-week period in a randomized controlled trial in Vietnam. HCWs were instructed to record their daily activities in diary cards. Demographic, clinical, and diary card data were used to determine the predictors of compliance and the relationship of compliance with infection outcomes. Results: Compliance rates for both medical and cloth masks decreased during the 4 weeks: medical mask use decreased from 77 to 68% (P < 0.001) and cloth masks from 78 to 69% (P < 0.001). The presence of adverse events (adjusted RR 0.90, 95% CI 0.85–0.95), and performing aerosol-generating procedures (adjusted RR 0.78, 95% CI 0.73–0.82) were negatively associated with compliance, while contact with febrile respiratory illness patients was positively associated (adjusted RR 1.14, 95% CI 1.07–1.20). Being compliant with medical or cloth masks use (average use ≥70% of working time) was not associated with clinical respiratory illness, influenza-like illness, and laboratory-confirmed viral infection. Conclusion: Understanding the factors that affect compliance is important for the occupational health and safety of HCWs. New strategies and tools should be developed to increase compliance of HCWs. The presence of adverse events such as discomfort and breathing problems may be the main reasons for the low compliance with mask use and further studies should be conducted to improve the design/material of masks to improve comfort for the wearer.
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Importance Contamination of the skin and clothing of health care personnel during removal of personal protective equipment (PPE) contributes to dissemination of pathogens and places personnel at risk for infection.Objectives To determine the frequency and sites of contamination on the skin and clothing of personnel during PPE removal and to evaluate the effect of an intervention on the frequency of contamination.Design, Setting, and Participants We conducted a point-prevalence study and quasi-experimental intervention from October 28, 2014, through March 31, 2015. Data analysis began November 17, 2014, and ended April 21, 2015. Participants included a convenience sample of health care personnel from 4 Northeast Ohio hospitals who conducted simulations of contaminated PPE removal using fluorescent lotion and a cohort of health care personnel from 7 study units in 1 medical center that participated in a quasi-experimental intervention that included education and practice in removal of contaminated PPE with immediate visual feedback based on fluorescent lotion contamination of skin and clothing.Main Outcomes and Measures The primary outcomes were the frequency and sites of contamination on skin and clothing of personnel after removal of contaminated gloves or gowns at baseline vs after the intervention. A secondary end point focused on the correlation between contamination of skin with fluorescent lotion and bacteriophage MS2, a nonpathogenic, nonenveloped virus.Results Of 435 glove and gown removal simulations, contamination of skin or clothing with fluorescent lotion occurred in 200 (46.0%), with a similar frequency of contamination among the 4 hospitals (range, 42.5%-50.3%). Contamination occurred more frequently during removal of contaminated gloves than gowns (52.9% vs 37.8%, P = .002) and when lapses in technique were observed vs not observed (70.3% vs 30.0%, P < .001). The intervention resulted in a reduction in skin and clothing contamination during glove and gown removal (60.0% before the intervention vs 18.9% after, P < .001) that was sustained after 1 and 3 months (12.0% at both time points, P < .001 compared with before the intervention). During simulations of contaminated glove removal, the frequency of skin contamination was similar with fluorescent lotion and bacteriophage MS2 (58.0% vs 52.0%, P = .45).Conclusions and Relevance Contamination of the skin and clothing of health care personnel occurs frequently during removal of contaminated gloves or gowns. Educational interventions that include practice with immediate visual feedback on skin and clothing contamination can significantly reduce the risk of contamination during removal of PPE.
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A cross-sectional survey was conducted in 89 secondary- and tertiary-level hospitals in 3 countries, and samples of masks and respirators were also collected and examined. Results showed varied practices around the use of masks and respirators, which are probably influenced by the available resources and local recommendations. Nonstandardized practices are common in low-resource settings, which may be placing health care workers at risk. Copyright © 2015 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.
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In the current era of emerging pathogens such as Ebola virus, removal of personal protective equipment (PPE) is crucial to reduce contamination of health care workers. However, current removal practices are not well described. We undertook a systematic evaluation of health care worker removal of PPE for contact isolation to examine variation in removal procedures. Findings indicate that under usual conditions, only about half of health care workers correctly remove their PPE, and very few remove their PPE in the correct order and dispose of it in the proper location. Published by Elsevier Inc.
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Background: There is an ongoing debate regarding the type of respiratory protection that should be recommended for use for healthcare workers. Materials and methods: A cross-sectional survey was conducted in three countries: China, Pakistan and Vietnam. Results: In China and Pakistan, the infection control guidelines were developed to be in line with the recommendations from the World Health Organization (WHO) and the Centers for Disease Control and Prevention, while in the Vietnamese guidelines the recommendations correspond with the WHO suggestions only. The guidelines from all three countries document the need for training and fit testing; however there is no system to monitor the training and fit testing programs. Across the three countries, there was some inconsistency with regard to the types of products (i.e. masks vs. respirators) recommended for influenza, severe acute respiratory syndrome (SARS) and tuberculosis. Conclusions: Available evidence should be examined and a comprehensive policy should be developed on the use of masks and respirators. The policy should address critical areas such as regulation, training, fit testing and reuse.
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Background: The aim of this study was to describe the risk of self-contamination associated with doffing of personal protective equipment (PPE) and to compare self-contamination with various PPE protocols. Methods: We tested 10 different PPE donning and doffing protocols, recommended by various health organizations for Ebola. Ten participants were recruited for this study and randomly assigned to use 3 different PPE protocols. After donning of PPE, fluorescent lotion and spray were applied on the external surface of the PPE to simulate contamination, and ultraviolet light was used to count fluorescent patches on the skin. Results: After testing 30 PPE sequences, large fluorescent patches were recorded after using "WHO coverall and 95" and "North Carolina coverall and N95" sequences, and small patches were recorded after using "CDC coverall and N95" and "Health Canada gown and N95" sequences. Commonly reported problems with PPE use were breathing difficulty, suffocation, heat stress, and fogging-up glasses. Most participants rated PPE high (18/30) or medium (11/30) for ease of donning/doffing and comfort. PPE sequences with powered air-purifying respirators (PAPRs) and assisted doffing were generally associated with fewer problems and were rated the highest. Conclusion: This study confirmed the risk of self-contamination associated with the doffing of PPE. PAPR-containing protocols and assisted doffing should be preferred whenever possible during the outbreak of highly infectious pathogens.
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Nosocomial transmission of respiratory syncytial virus (RSV) occurs in children within the neonatal intensive care unit (NICU). During peak community RSV transmission, three swabs were collected from the nose, hand and personal clothing of visitors and health care workers (HCW) in NICU once every week for eight weeks. Nasal swabs were collected from every third neonate and from any neonate clinically suspected of having a respiratory infection. Environmental sampling of high touch areas was done once during the study period. All swabs were tested for RSV using real time RT-PCR. There were 173 (519 total) and 109 (327 total) swabs, each of nose, hand and dress from 84 HCWs and 80 visitors respectively and 81 nasal swabs from 55 neonates collected. Thirty five environmental swabs from surfaces of the beds, side tables, counter tops, chairs, tables and computers were collected. Overall 1% of nasal swabs from each of HCWs, visitors and neonates, 4% of dress specimens from visitors and 9% of environmental swabs were positive for RSV-RNA. The results suggest that though the risk for RSV in the NICU remains low, personnel clothing are contaminated with RSV-RNA and may have a role in transmission. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
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This study aimed to examine the knowledge, attitudes, and practices towards the use of facemasks among hospital-based health care workers (HCWs) in Hanoi, Vietnam. A qualitative study incorporating 20 focus groups was conducted between August 2010 and May 2011. HCWs from 7 hospitals in Vietnam were invited to participate. Issues associated with the availability of facemasks (medical and cloth masks) and respirators was the strongest theme to emerge from the discussion. Participants reported that it is not unusual for some types of facemasks to be unavailable during nonemergency periods. It was highlighted that the use of facemasks and respirators is not continuous, but rather is limited to selected situations, locations, and patients. Reuse of facemasks and respirators is also common in some settings. Finally, some participants reported believing that the reuse of facemasks, particularly cloth masks, is safe, whereas others believed that the reuse of masks put staff at risk of infection. In low and middle-income countries, access to appropriate levels of personal protective equipment may be restricted owing to competing demands for funding in hospital settings. It is important that issues around reuse and extended use of medical masks/respirators and decontamination of cloth masks are addressed in policy documents to minimize the risk of infection. Copyright © 2015 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.