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Abstract

Objective The aim of this study was to compare the efficacy of cloth masks to medical masks in hospital healthcare workers (HCWs). The null hypothesis is that there is no difference between medical masks and cloth masks. Setting 14 secondary-level/tertiary-level hospitals in Hanoi, Vietnam. Participants 1607 hospital HCWs aged ≥18 years working full-time in selected high-risk wards. Intervention Hospital wards were randomised to: medical masks, cloth masks or a control group (usual practice, which included mask wearing). Participants used the mask on every shift for 4 consecutive weeks. Main outcome measure Clinical respiratory illness (CRI), influenza-like illness (ILI) and laboratory-confirmed respiratory virus infection. Results The rates of all infection outcomes were highest in the cloth mask arm, with the rate of ILI statistically significantly higher in the cloth mask arm (relative risk (RR)=13.00, 95% CI 1.69 to 100.07) compared with the medical mask arm. Cloth masks also had significantly higher rates of ILI compared with the control arm. An analysis by mask use showed ILI (RR=6.64, 95% CI 1.45 to 28.65) and laboratory-confirmed virus (RR=1.72, 95% CI 1.01 to 2.94) were significantly higher in the cloth masks group compared with the medical masks group. Penetration of cloth masks by particles was almost 97% and medical masks 44%. Conclusions This study is the first RCT of cloth masks, and the results caution against the use of cloth masks. This is an important finding to inform occupational health and safety. Moisture retention, reuse of cloth masks and poor filtration may result in increased risk of infection. Further research is needed to inform the widespread use of cloth masks globally. However, as a precautionary measure, cloth masks should not be recommended for HCWs, particularly in high-risk situations, and guidelines need to be updated. Trial registration number Australian New Zealand Clinical Trials Registry: ACTRN12610000887077.
A cluster randomised trial of cloth
masks compared with medical masks
in healthcare workers
C Raina MacIntyre,
1
Holly Seale,
1
Tham Chi Dung,
2
Nguyen Tran Hien,
2
Phan Thi Nga,
2
Abrar Ahmad Chughtai,
1
Bayzidur Rahman,
1
Dominic E Dwyer,
3
Quanyi Wang
4
To cite: MacIntyre CR,
Seale H, Dung TC, et al.
A cluster randomised trial of
cloth masks compared with
medical masks in healthcare
workers. BMJ Open 2015;5:
e006577. doi:10.1136/
bmjopen-2014-006577
Prepublication history for
this paper is available online.
To view these files please
visit the journal online
(http://dx.doi.org/10.1136/
bmjopen-2014-006577).
Received 9 September 2014
Revised 25 March 2015
Accepted 26 March 2015
For numbered affiliations see
end of article.
Correspondence to
Professor C Raina MacIntyre;
r.macintyre@unsw.edu.au
ABSTRACT
Objective: The aim of this study was to compare the
efficacy of cloth masks to medical masks in hospital
healthcare workers (HCWs). The null hypothesis is that
there is no difference between medical masks and
cloth masks.
Setting: 14 secondary-level/tertiary-level hospitals in
Hanoi, Vietnam.
Participants: 1607 hospital HCWs aged 18 years
working full-time in selected high-risk wards.
Intervention: Hospital wards were randomised to:
medical masks, cloth masks or a control group
(usual practice, which included mask wearing).
Participants used the mask on every shift for 4
consecutive weeks.
Main outcome measure: Clinical respiratory illness
(CRI), influenza-like illness (ILI) and laboratory-
confirmed respiratory virus infection.
Results: The rates of all infection outcomes were
highest in the cloth mask arm, with the rate of ILI
statistically significantly higher in the cloth mask arm
(relative risk (RR)=13.00, 95% CI 1.69 to 100.07)
compared with the medical mask arm. Cloth masks
also had significantly higher rates of ILI compared with
the control arm. An analysis by mask use showed ILI
(RR=6.64, 95% CI 1.45 to 28.65) and laboratory-
confirmed virus (RR=1.72, 95% CI 1.01 to 2.94) were
significantly higher in the cloth masks group compared
with the medical masks group. Penetration of cloth
masks by particles was almost 97% and medical
masks 44%.
Conclusions: This study is the first RCT of cloth
masks, and the results caution against the use of cloth
masks. This is an important finding to inform
occupational health and safety. Moisture retention,
reuse of cloth masks and poor filtration may result in
increased risk of infection. Further research is needed
to inform the widespread use of cloth masks globally.
However, as a precautionary measure, cloth masks
should not be recommended for HCWs, particularly in
high-risk situations, and guidelines need to be
updated.
Trial registration number: Australian New Zealand
Clinical Trials Registry: ACTRN12610000887077.
INTRODUCTION
The use of facemasks and respirators for the
protection of healthcare workers (HCWs)
has received renewed interest following the
2009 inuenza pandemic,
1
and emerging
infectious diseases such as avian inuenza,
2
Middle East respiratory syndrome corona-
virus (MERS-coronavirus)
34
and Ebola
virus.
5
Historically, various types of cloth/
cotton masks (referred to here after as cloth
masks) have been used to protect HCWs.
6
Disposable medical/surgical masks (referred
to here after as medical masks) were intro-
duced into healthcare in the mid 19th
century, followed later by respirators.
7
Compared with other parts of the world, the
use of face masks is more prevalent in Asian
countries, such as China and Vietnam.
811
In high resource settings, disposable
medical masks and respirators have long
since replaced the use of cloth masks in hos-
pitals. Yet cloth masks remain widely used
Strengths and limitations of this study
The use of cloth masks is widespread around
the world, particularly in countries at high-risk
for emerging infections, but there have been no
efficacy studies to underpin their use.
This study is large, a prospective randomised
clinical trial (RCT) and the first RCT ever con-
ducted of cloth masks.
The use of cloth masks are not addressed in
most guidelines for health care workersthis
study provides data to update guidelines.
The control arm was standard practice, which
comprised mask use in a high proportion of par-
ticipants. As such (without a no-mask control),
the finding of a much higher rate of infection in
the cloth mask arm could be interpreted as harm
caused by cloth masks, efficacy of medical
masks, or most likely a combination of both.
MacIntyre CR, et al.BMJ Open 2015;5:e006577. doi:10.1136/bmjopen-2014-006577 1
Open Access Research
globally, including in Asian countries, which have histor-
ically been affected by emerging infectious diseases, as
well as in West Africa, in the context of shortages of per-
sonal protective equipment (PPE).
12 13
It has been
shown that medical research disproportionately favours
diseases of wealthy countries, and there is a lack of
research on the health needs of poorer countries.
14
Further, there is a lack of high-quality studies around the
use of facemasks and respirators in the healthcare
setting, with only four randomised clinical trials (RCTs)
to date.
15
Despite widespread use, cloth masks are rarely
mentioned in policy documents,
16
and have never been
tested for efcacy in a RCT. Very few studies have been
conducted around the clinical effectiveness of cloth
masks, and most available studies are observational or in
vitro.
6
Emerging infectious diseases are not constrained
within geographical borders, so it is important for global
disease control that use of cloth masks be underpinned
by evidence. The aim of this study was to determine the
efcacy of cloth masks compared with medical masks in
HCWs working in high-risk hospital wards, against the
prevention of respiratory infections.
METHODS
A cluster-randomised trial of medical and cloth mask
use for HCWs was conducted in 14 hospitals in Hanoi,
Vietnam. The trial started on the 3 March 2011, with
rolling recruitment undertaken between 3 March 2011
and 10 March 2011. Participants were followed during
the same calendar time for 4 weeks of facemasks use
and then one additional week for appearance of symp-
toms. An invitation letter was sent to 32 hospitals in
Hanoi, of which 16 agreed to participate. One hospital
did not meet the eligibility criteria; therefore, 74 wards
in 15 hospitals were randomised. Following the random-
isation process, one hospital withdrew from the study
because of a nosocomial outbreak of rubella.
Participants provided written informed consent prior
to initiation of the trial.
Randomisation
Seventy-four wards (emergency, infectious/respiratory
disease, intensive care and paediatrics) were selected as
high-risk settings for occupational exposure to respira-
tory infections. Cluster randomisation was used because
the outcome of interest was respiratory infectious dis-
eases, where prevention of one infection in an individual
can prevent a chain of subsequent transmission in
closed settings.
89
Epi info V.6 was used to generate a
randomisation allocation and 74 wards were randomly
allocated to the interventions.
From the eligible wards 1868 HCWs were approached
to participate. After providing informed consent, 1607
participants were randomised by ward to three arms:
(1) medical masks at all times on their work shift; (2)
cloth masks at all times on shift or (3) control arm
(standard practice, which may or may not include mask
use). Standard practice was used as control because the
IRB deemed it unethical to ask participants to not wear
a mask. We studied continuous mask use (dened as
wearing masks all the time during a work shift, except
while in the toilet or during tea or lunch breaks)
because this reects current practice in high-risk settings
in Asia.
8
Figure 1 Consort diagram of
recruitment and follow-up (HCWs,
healthcare workers).
2MacIntyre CR, et al.BMJ Open 2015;5:e006577. doi:10.1136/bmjopen-2014-006577
Open Access
The laboratory results were blinded and laboratory
testing was conducted in a blinded fashion. As facemask
use is a visible intervention, clinical end points could
not be blinded. Figure 1 outlines the recruitment and
randomisation process.
Primary end points
There were three primary end points for this study, used in
our previous mask RCTs:
89
(1) Clinical respiratory illness
(CRI), dened as two or more respiratory symptoms or
one respiratory symptom and a systemic symptom;
17
(2) inuenza-like illness (ILI), dened as fever 38°C plus
one respiratory symptom and (3) laboratory-conrmed
viral respiratory infection. Laboratory conrmation was by
nucleic acid detection using multiplex reverse transcript-
ase PCR (RT-PCR) for 17 respiratory viruses: respiratory
syncytial virus (RSV) A and B, human metapneumovirus
(hMPV), inuenza A (H3N2), (H1N1)pdm09, inuenza
B, parainuenza viruses 14, inuenza C, rhinoviruses,
severe acute respiratory syndrome (SARS) associated
coronavirus (SARS-CoV), coronaviruses 229E, NL63,
OC43 and HKU1, adenoviruses and human bocavirus
(hBoV).
1823
Additional end points included compliance
with mask use, dened as using the mask during the shift
for 70% or more of work shift hours.
9
HCWs were cate-
gorised as compliantif the average use was equal or more
than 70% of the working time. HCW were categorised as
non-compliantif the average mask use was less than 70%
of the working time.
Eligibility
Nurses or doctors aged 18 years working full-time were
eligible. Exclusion criteria were: (1) Unable or refused
to consent; (2) Beards, long moustaches or long facial
hair stubble; (3) Current respiratory illness, rhinitis
and/or allergy.
Intervention
Participants wore the mask on every shift for four con-
secutive weeks. Participants in the medical mask arm
were supplied with two masks daily for each 8 h shift,
while participants in the cloth mask arm were provided
with ve masks in total for the study duration, which
they were asked to wash and rotate over the study
period. They were asked to wash cloth masks with soap
and water every day after nishing the shifts.
Participants were supplied with written instructions on
how to clean their cloth masks. Masks used in the study
were locally manufactured medical (three layer, made of
non-woven material) or cloth masks (two layer, made of
cotton) commonly used in Vietnamese hospitals. The
control group was asked to continue with their normal
practices, which may or may not have included mask
wearing. Mask wearing was measured and documented
for all participants, including the control arm.
Data collection and follow-up
Data on sociodemographic, clinical and other potential
confounding factors were collected at baseline.
Participants were followed up daily for 4 weeks (active
intervention period), and for an extra week of standard
practice, in order to document incident infection after
incubation. Participants received a thermometer (trad-
itional glass and mercury) to measure their temperature
daily and at symptom onset. Daily diary cards were pro-
vided to record number of hours worked and mask use,
estimated number of patient contacts (with/without ILI)
and number/type of aerosol-generating procedures
(AGPs) conducted, such as suctioning of airways,
sputum induction, endotracheal intubation and bron-
choscopy. Participants in the cloth mask and control
group (if they used cloth masks) were also asked to
document the process used to clean their mask
after use.
We also monitored compliance with mask use by a pre-
viously validated self-reporting mechanism.
8
Participants
were contacted daily to identify incident cases of respira-
tory infection. If participants were symptomatic, swabs of
both tonsils and the posterior pharyngeal wall were col-
lected on the day of reporting.
Sample collection and laboratory testing
Trained collectors used double rayon-tipped, plastic-
shafted swabs to scratch tonsillar areas as well as the pos-
terior pharyngeal wall of symptomatic participants.
Testing was conducted using RT-PCR applying published
methods.
1923
Viral RNA was extracted from each respira-
tory specimen using the Viral RNA Mini kit (Qiagen,
Germany), following the manufacturers instructions.
The RNA extraction step was controlled by amplication
of a RNA house-keeping gene (amplify pGEM) using
real-time RT-PCR. Only extracted samples with the house
keeping gene detected by real-time RT-PCR were submit-
ted for multiplex RT-PCR for viruses.
The reverse transcription and PCRs were performed
in OneStep (Qiagen, Germany) to amplify viral target
genes, and then in ve multiplex RT-PCR: RSVA/B,
inuenza A/H3N2, A(H1N1) and B viruses, hMPV
(reaction mix 1); parainuenza viruses 14 (reaction
mix 2); rhinoviruses, inuenza C virus, SARS-CoV (reac-
tion mix 3); coronaviruses OC43, 229E, NL63 and
HKU1 (reaction mix 4); and adenoviruses and hBoV
(reaction mix 5), using a method published by others.
18
All samples with viruses detected by multiplex RT-PCR
were conrmed by virus-specic mono nested or hemi-
nested PCR. Positive controls were prepared by in vitro
transcription to control amplication efcacy and
monitor for false negatives, and included in all runs
(except for NL63 and HKU1). Each run always included
two negatives to monitor amplication quality. Specimen
processing, RNA extraction, PCR amplication and PCR
product analyses were conducted in different rooms to
avoid cross-contamination.
19 20
MacIntyre CR, et al.BMJ Open 2015;5:e006577. doi:10.1136/bmjopen-2014-006577 3
Open Access
Filtration testing
The ltration performance of the cloth and medical
masks was tested according to the respiratory standard
AS/NZS1716.
24
The equipment used was a TSI 8110
Filter tester. To test the ltration performance, the lter
is challenged by a known concentration of sodium chlor-
ide particles of a specied size range and at a dened
ow rate. The particle concentration is measured before
and after adding the lter material and the relative
ltration efciency is calculated. We examined the
performance of cloth masks compared with the per-
formance levelsP1, P2 (=N95) and P3, as used for
assessment of all particulate lters for respiratory protec-
tion. The 3M 9320 N95 and 3M Vex 9105 N95 were
used to compare against the cloth and medical masks.
Sample size calculation
To obtain 80% power at two-sided 5% signicance level
for detecting a signicant difference of attack rate
between medical masks and cloth masks, and for a rate
of infection of 13% for cloth mask wearers compared
with 6% in medical mask wearers, we would need eight
clusters per arm and 530 participants in each arm, and
intracluster correlation coefcient (ICC) 0.027, obtained
from our previous study.
8
The design effect (deff ) for
this cluster randomisation trial was 1.65 (deff=1+(m
1)×ICC=1+(251)×0.027=1.65). As such, we aimed to
recruit a sample size of 1600 participants from up to 15
hospitals.
Analysis
Descriptive statistics were compared among intervention
and control arms. Primary end points were analysed by
intention to treat. We compared the event rates for the
primary outcomes across study arms and calculated
p values from cluster-adjusted χ
2
tests
25
and ICC.
25 26
We
also estimated relative risk (RR) after adjusting for clus-
tering using a log-binomial model under generalised
estimating equation (GEE) framework.
27
We checked for
variables which were unequally distributed across arms,
and conducted an adjusted analysis accordingly. We
tted a multivariable log-binomial model, using GEE to
account for clustering by ward, to estimate RR after
adjusting for potential confounders. In the initial
model, we included all the variables that had p value
less than 0.25 in the univariable analysis, along with the
main exposure variable (randomisation arm). A back-
ward elimination method was used to remove the vari-
ables that did not have any confounding effect.
As most participants in the control arm used a mask
during the trial period, we carried out a post-hoc ana-
lysis comparing all participants who used only a medical
mask (from the control arm and the medical mask arm)
with all participants who used only a cloth mask ( from
the control arm and the cloth arm). For this analysis,
controls who used both types of mask (n=245) or used
N95 respirators (n=3) or did not use any masks (n=2)
were excluded. We tted a multivariable log-binomial
model, to estimate RR after adjusting for potential con-
founders. As we pooled data of participants from all
three arms and analysed by mask type, not trial arm, we
did not adjust for clustering here. All statistical analyses
were conducted using STATA V.12.
28
Owing to a very high level of mask use in the control
arm, we were unable to determine whether the differ-
ences between the medical and cloth mask arms were
due to a protective effect of medical masks or a detri-
mental effect of cloth masks. To assist in interpreting
the data, we compared rates of infection in the medical
mask arm with rates observed in medical mask arms
from two previous RCTs,
89
in which no efcacy of
medical masks could be demonstrated when compared
with control or N95 respirators, recognising that sea-
sonal and geographic variation in virus activity affects
the rates of exposure (and hence rates of infection out-
comes) among HCWs. This analysis was possible because
the trial designs were similar and the same outcomes
were measured in all three trials. The analysis was
carried out to determine if the observed results were
explained by a detrimental effect of cloth masks or a
protective effect of medical masks.
RESULTS
A total of 1607 HCWs were recruited into the study. The
participation rate was 86% (1607/1868). The average
number of participants per ward was 23 and the mean
age was 36 years. On average, HCWs were in contact
with 36 patients per day during the trial period (range
0661 patients per day, median 20 patients per day).
The distribution of demographic variables was generally
similar between arms (table 1). Figure 2 shows the
primary outcomes for each of the trial arms. The rates
of CRI, ILI and laboratory-conrmed virus infections
were lowest in the medical mask arm, followed by the
control arm, and highest in the cloth mask arm.
Table 2 shows the intention-to-treat analysis. The rate
of CRI was highest in the cloth mask arm, followed by
the control arm, and lowest in the medical mask arm.
The same trend was seen for ILI and laboratory tests
conrmed viral infections. In intention-to-treat analysis,
ILI was signicantly higher among HCWs in the cloth
masks group (RR=13.25 and 95% CI 1.74 to 100.97),
compared with the medical masks group. The rate of
ILI was also signicantly higher in the cloth masks arm
(RR=3.49 and 95% CI 1.00 to 12.17), compared with the
control arm. Other outcomes were not statistically signi-
cant between the three arms.
Among the 68 laboratory-conrmed cases, 58 (85%)
were due to rhinoviruses. Other viruses detected were
hMPV (7 cases), inuenza B (1 case), hMPV/rhinovirus
co-infection (1 case) and inuenza B/rhinovirus
co-infection (1 case) (table 3). No inuenza A or RSV
infections were detected.
Compliance was signicantly higher in the cloth mask
arm (RR=2.41, 95% CI 2.01 to 2.88) and medical masks
4MacIntyre CR, et al.BMJ Open 2015;5:e006577. doi:10.1136/bmjopen-2014-006577
Open Access
arm (RR=2.40, 95% CI 2.00 to 2.87), compared with the
control arm. Figure 3 shows the percentage of partici-
pants who were compliant in the three arms. A post-hoc
analysis adjusted for compliance and other potential con-
founders showed that the rate of ILI was signicantly
higher in the cloth mask arm (RR=13.00, 95% CI 1.69 to
100.07), compared with the medical masks arm (table 4).
There was no signicant difference between the medical
mask and control arms. Hand washing was signicantly
protective against laboratory-conrmed viral infection
(RR=0.66, 95% CI 0.44 to 0.97).
In the control arm, 170/458 (37%) used medical
masks, 38/458 (8%) used cloth masks, and 245/458
(53%) used a combination of both medical and cloth
masks during the study period. The remaining 1%
either reported using a N95 respirator (n=3) or did not
use any masks (n=2).
Table 5 shows an additional analysis comparing all par-
ticipants who used only a medical mask ( from the
control arm and the medical mask arm) with all partici-
pants who used only a cloth mask (from the control arm
and the cloth arm). In the univariate analysis, all out-
comes were signicantly higher in the cloth mask group,
compared with the medical masks group. After adjusting
for other factors, ILI (RR=6.64, 95% CI 1.45 to 28.65)
and laboratory-conrmed virus (RR=1.72, 95% CI 1.01
to 2.94) remained signicantly higher in the cloth masks
group compared with the medical masks group.
Table 6 compares the outcomes in the medical mask
arm with two previously published trials.
89
This shows
that while the rates of CRI were signicantly higher in
one of the previously published trials, the rates of
laboratory-conrmed viruses were not signicantly differ-
ent between the three trials for medical mask use.
On average, HCWs worked for 25 days during the trial
period and washed their cloth masks for 23/25 (92%)
days. The most common approach to washing cloth
masks was self-washing (456/569, 80%), followed by
combined self-washing and hospital laundry (91/569,
16%), and only hospital laundry (22/569, 4%). Adverse
events associated with facemask use were reported in
40.4% (227/562) of HCWs in the medical mask arm
and 42.6% (242/568) in the cloth mask arm ( p value
0.450). General discomfort (35.1%, 397/1130) and
breathing problems (18.3%, 207/1130) were the most
frequently reported adverse events.
Table 1 Demographic and other characteristics by arm of randomisation
Variable
Medical mask
(% and 95% CI)
(n=580)
Cloth mask
(% and 95% CI)
(n=569)
Control
(% and 95% CI)
(n=458)
Gender (male) 112/580
19.3 (16.2 to 22.8)
133/569
23.4 (20.0 to 27.1)
112/458
24.5 (20.6 to 28.7)
Age (mean) 36 (35.6 to 37.3) 35 (34.6 to 36.3) 36 (35.1 to 37.0)
Education (postgraduate) 114/580
19.7 (16.5 to 23.1)
99/569
17.4 (14.3 to 20.8)
78/458
17.0 (13.7 to 20.8)
Smoker (current/ex) 78/580
13.4 (10.8 to 16.5)
79/569
13.9 (11.1 to 17.0)
66/458
14.4 (11.3 to 18.0)
Pre-existing illness* 66/580
11.4 (9.0 to 14.2)
70/569
12.3 (9.8 to 15.3)
47/458
10.3 (7.8 to 13.4)
Influenza vaccination (yes) 21/580
3.6 (2.4 to 5.4)
21/569
3.7 (2.4 to 5.6)
15/458
3.3 (2.0 to 5.3)
Staff (doctors) 176/580
30.3 (26.6 to 34.3)
165/569
29.0 (25.3 to 32.9)
134/458
29.3 (25.1 to 33.7)
Number of hand washings per day
(geometric mean)
14 (13.8 to 15.4) 11 (10.9 to 11.9) 12 (11.5 to 12.7)
Number of patients had contact with
(median and range)
21 (0 to 540) 21 (0 to 661) 18 (3 to 199)
*Includes asthma, immunocompromised and others.
†‘Hand washvariable was created by taking average of the number of hand washes performed by a healthcare worker (HCW) over the trial
period. The variable was log transformed for the multivariate analysis.
‡‘Number of patients had contact withvariable was created by taking average of the number of patients in contact with a HCW over the trial
period. Median and range is presented in the table.
Figure 2 Outcomes in trial arms (CRI, clinical respiratory
illness; ILI, influenza-like illness; Virus, laboratory-confirmed
viruses).
MacIntyre CR, et al.BMJ Open 2015;5:e006577. doi:10.1136/bmjopen-2014-006577 5
Open Access
Laboratory tests showed the penetration of particles
through the cloth masks to be very high (97%) com-
pared with medical masks (44%) (used in trial) and 3M
9320 N95 (<0.01%), 3M Vex 9105 N95 (0.1%).
DISCUSSION
We have p r o v ided t h e rst clinical efcacy data of cloth
masks, which suggest HCWs should not use cloth masks as
protection against respiratory infection. Cloth masks
resulted in signicantly higher rates of infection than
medical masks, and also performed worse than the control
arm. The controls were HCWs who observed standard prac-
tice, which involved mask use in the majority, albeit with
lower compliance than in the intervention arms. The
control HCWs also used medical masks more often than
cloth masks. When we analysed all mask-wearers including
controls, the higher risk of cloth masks was seen for
laboratory-conrmed respiratory viral infection.
The trend for all outcomes showed the lowest rates of
infection in the medical mask group and the highest
rates in the cloth mask arm. The study design does not
allow us to determine whether medical masks had ef-
cacy or whether cloth masks were detrimental to HCWs
by causing an increase in infection risk. Either possibil-
ity, or a combination of both effects, could explain our
results. It is also unknown whether the rates of infection
observed in the cloth mask arm are the same or higher
than in HCWs who do not wear a mask, as almost all
participants in the control arm used a mask. The phys-
ical properties of a cloth mask, reuse, the frequency and
effectiveness of cleaning, and increased moisture reten-
tion, may potentially increase the infection risk for
HCWs. The virus may survive on the surface of the face-
masks,
29
and modelling studies have quantied the con-
tamination levels of masks.
30
Self-contamination through
repeated use and improper dofng is possible. For
example, a contaminated cloth mask may transfer patho-
gen from the mask to the bare hands of the wearer. We
also showed that ltration was extremely poor (almost
0%) for the cloth masks. Observations during SARS sug-
gested double-masking and other practices increased the
risk of infection because of moisture, liquid diffusion
and pathogen retention.
31
These effects may be asso-
ciated with cloth masks.
We have previously shown that N95 respirators provide
superior efcacy to medical masks,
89
but need to be
worn continuously in high-risk settings to protect HCWs.
9
Although efcacy for medical masks was not shown, ef-
cacy of a magnitude that was too small to be detected is
possible.
89
The magnitude of difference between cloth
masks and medical masks in the current study, if
explained by efcacy of medical masks alone, translates
to an efcacy of 92% against ILI, which is possible, but
not consistent with the lack of efcacy in the two previous
RCTs.
89
Further, we found no signicant difference in
rates of virus isolation in medical mask users between the
three trials, suggesting that the results of this study could
be interpreted as partly being explained by a detrimental
effect of cloth masks. This is further supported by the
fact that the rate of virus isolation in the no-mask control
group in the rst Chinese RCT was 3.1%, which was not
signicantly different to the rates of virus isolation in the
medical mask arms in any of the three trials including
this one. Unlike the previous RCTs, circulating inuenza
and RSV were almost completely absent during this study,
Table 2 Intention-to-treat analysis
CRI
N (%)
RR
(95% CI)
ILI
N (%)
RR
(95% CI)
Laboratory-
confirmed
viruses
N (%)
RR
(95% CI)
Medical mask* 28/580 (4.83) Ref 1/580 (0.17) Ref 19/580 (3.28) Ref
Cloth masks43/569 (7.56) 1.57 (0.99 to 2.48) 13/569 (2.28) 13.25 (1.74 to 100.97) 31/569 (5.45) 1.66 (0.95 to 2.91)
Control32/458 (6.99) 1.45 (0.88 to 2.37) 3/458 (0.66) 3.80 (0.40 to 36.40) 18/458 (3.94) 1.20 (0.64 to 2.26)
Bold typeface indicates statistically significant.
*p Value from cluster adjusted χ
2
tests is 0.510 and intracluster correlation coefficients is 0.065.
p Value from cluster adjusted χ
2
tests is 0.028 and intracluster correlation coefficients is 0.029.
p Value from cluster adjusted χ
2
tests is 0.561 and intracluster correlation coefficients is 0.068.
CRI, clinical respiratory illness; ILI, influenza-like illness; RR, relative risk.
Table 3 Type of virus isolated
Study arm hMPV Rhino
Influenza
B virus
hMPV &
rhino
Influenza
B virus & rhino Total
Medical masks arm 1 16 1 1 0 19
Cloth mask arm 4 26 0 0 1 31
Control arm 2 16 0 0 0 18
Total 7 58 1 1 1 68
hMPV, human metapneumovirus; Rhino, rhinoviruses.
6MacIntyre CR, et al.BMJ Open 2015;5:e006577. doi:10.1136/bmjopen-2014-006577
Open Access
with rhinoviruses comprising 85% of isolated pathogens,
which means the measured efcacy is against a different
range of circulating respiratory pathogens. Inuenza and
RSV predominantly transmit through droplet and
contact routes, while Rhinovirus transmits through mul-
tiple routes, including airborne and droplet routes.
32 33
The data also show that the clinical case denition of ILI
is non-specic, and captures a range of pathogens other
than inuenza. The study suggests medical masks may be
protective, but the magnitude of difference raises the pos-
sibility that cloth masks cause an increase in infection risk
in HCWs. Further, the ltration of the medical mask used
in this trial was poor, making extremely high efcacy of
medical masks unlikely, particularly given the predomin-
ant pathogen was rhinovirus, which spreads by the air-
borne route. Given the obligations to HCW occupational
health and safety, it is important to consider the potential
risk of using cloth masks.
In many parts of the world, cloth masks and medical
masks may be the only options available for HCWs.
Cloth masks have been used in West Africa during the
Ebola outbreak in 2014, due to shortages of PPE, (per-
sonal communication, M Jalloh). The use of cloth masks
is recommended by some health organisations, with
caveats.
3436
In light of our study, and the obligation to
ensure occupational health and safety of HCWs, cloth
masks should not be recommended for HCWs, particu-
larly during AGPs and in high-risk settings such as emer-
gency, infectious/respiratory disease and intensive care
wards. Infection control guidelines need to acknowledge
the widespread real-world practice of cloth masks and
should comprehensively address their use. In addition,
other important infection control measure such as hand
hygiene should not be compromised. We conrmed the
protective effects of hand hygiene against laboratory-
conrmed viral infection in this study, but mask type was
an independent predictor of clinical illness, even
adjusted for hand hygiene.
A limitation of this study is that we did not measure
compliance with hand hygiene, and the results reect
self-reported compliance, which may be subject to recall
or other types of bias. Another limitation of this study is
the lack of a no-mask control group and the high use of
masks in the controls, which makes interpretation of the
results more difcult. In addition, the quality of paper
and cloth masks varies widely around the world, so the
results may not be generalisable to all settings. The lack
of inuenza and RSV (or asymptomatic infections)
during the study is also a limitation, although the pre-
dominance of rhinovirus is informative about pathogens
transmitted by the droplet and airborne routes in this
setting. As in previous studies, exposure to infection
outside the workplace could not be estimated, but we
would assume it to be equally distributed between trial
arms. The major strength of the randomised trial study
design is in ensuring equal distribution of confounders
and effect modiers (such as exposure outside the work-
place) between trial arms.
Cloth masks are used in resource-poor settings because
of the reduced cost of a reusable option. Various types of
cloth masks (made of cotton, gauze and other bres)
have been tested in vitro in the past and show lower ltra-
tion capacity compared with disposable masks.
7
The pro-
tection afforded by gauze masks increases with the
neness of the cloth and the number of layers,
37
indicat-
ing potential to develop a more effective cloth mask, for
example, with ner weave, more layers and a better t.
Cloth masks are generally retained long term and
reused multiple times, with a variety of cleaning
methods and widely different intervals of cleaning.
34
Further studies are required to determine if variations in
frequency and type of cleaning affect the efcacy of
cloth masks.
Table 4 Multivariable cluster-adjusted log-binomial model to calculate RR for study outcomes
CRI
RR (95% CI)
ILI
RR (95% CI)
Laboratory-confirmed viruses
RR (95% CI)
Medical masks arm Ref Ref Ref
Cloth mask arm 1.56 (0.97 to 2.48) 13.00 (1.69 to 100.07) 1.54 (0.88 to 2.70)
Control arm 1.51 (0.90 to 2.52) 4.64 (0.47 to 45.97) 1.09 (0.57 to 2.09)
Male 0.67 (0.41 to 1.12) 1.03 (0.34 to 3.13) 0.65 (0.34 to 1.22)
Vaccination 0.83 (0.27 to 2.52) 1.74 (0.24 to 12.56) 1.27 (0.41 to 3.92)
Hand washing 0.91 (0.66 to 1.26) 0.94 (0.40 to 2.20) 0.66 (0.44 to 0.97)
Compliance 1.14 (0.77 to 1.69) 1.86 (0.67 to 5.21) 0.86 (0.53 to 1.40)
Bold typeface indicates statistically significant.
CRI, clinical respiratory illness; ILI, influenza-like illness; RR, relative risk.
Figure 3 Compliance with the mask wearingmask wearing
more than 70% of working hours.
MacIntyre CR, et al.BMJ Open 2015;5:e006577. doi:10.1136/bmjopen-2014-006577 7
Open Access
Pandemics and emerging infections are more likely to
arise in low-income or middle-income settings than in
wealthy countries. In the interests of global public
health, adequate attention should be paid to cloth mask
use in such settings. The data from this study provide
some reassurance about medical masks, and are the rst
data to show potential clinical efcacy of medical masks.
Medical masks are used to provide protection against
droplet spread, splash and spray of blood and body
uids. Medical masks or respirators are recommended
by different organisations to prevent transmission of
Ebola virus, yet shortages of PPE may result in HCWs
being forced to use cloth masks.
3840
In the interest of
providing safe, low-cost options in low income countries,
there is scope for research into more effectively
designed cloth masks, but until such research is carried
out, cloth masks should not be recommended. We also
recommend that infection control guidelines be
updated about cloth mask use to protect the occupa-
tional health and safety of HCWs.
Author affiliations
1
Faculty of Medicine, School of Public Health and Community Medicine,
University of New South Wales, Sydney, Australia
2
National Institute of Hygiene and Epidemiology, Hanoi, Vietnam
3
Institute for Clinical Pathology and Medical Research, Westmead Hospital
and University of Sydney, Sydney, New South Wales, Australia
4
Beijing Centers for Disease Control and Prevention, Beijing, China
Acknowledgements The authors would like to thank the staff members from
the National Institute of Hygiene and Epidemiology, Hanoi, Vietnam, who were
involved with the trial. They thank as well to the staff from the Hanoi hospitals
who participated. They also acknowledge the support of 3M for testing of
filtration of the facemasks. 3M was industry partner in the ARC linkage project
Table 5 Univariate and adjusted analysis comparing participants who used medical masks and cloth masks*
Univariate
RR (95% CI)
Adjusted
RR (95% CI)
CRI
Medical mask (35/750, 4.67%) Ref Ref
Cloth mask (46/607, 7.58%) 1.62 (1.06 to 2.49) 1.51 (0.97 to 2.32)
Male 0.60 (0.32 to 1.12) 0.58 (0.31 to 1.08)
Vaccination 0.66 (0.17 to 2.62) 0.68 (0.17 to 2.67)
Hand washing 0.81 (0.58 to 1.15) 0.84 (0.59 to 1.20)
Compliance 1.01 (1.00 to 1.03) 1.01 (1.00 to 1.02)
ILI
Medical mask (2/750, 0.27%) Ref Ref
Cloth mask (13/607, 2.14%) 8.03 (1.82 to 35.45) 6.64 (1.45 to 28.65)
Male 0.95 (0.27 to 3.35) 0.92 (0.26 to 3.22)
Vaccination 1.87 (0.25 to 13.92) 1.97 (0.27 to 14.45)
Hand washing 0.56 (0.24 to 1.27) 0.61 (0.23 to 1.57)
Compliance 1.04 (1.01 to 1.08) 1.04 (1.00 to 1.08)
Laboratory-confirmed viruses
Medical mask (22/750, 2.93%) Ref Ref
Cloth mask (34/607, 5.60%) 1.91 (1.13 to 3.23) 1.72 (1.01 to 2.94)
Male 0.64 (0.30 to 1.33) 0.61 (0.29 to 1.27)
Vaccination 0.97 (0.24 to 3.86) 1.03 (0.26 to 4.08)
Hand washing 0.61 (0.41 to 0.93) 0.65 (0.42 to 1.00)
Compliance 1.00 (0.99 to 1.02) 1.0 (0.99 to 1.02)
Bold typeface indicates statistically significant.
*The majority (456/458) of HCWs in the control arm used a mask. Controls who exclusively used a medical mask were categorised and
analysed with the medical mask arm participants; and controls who exclusively wore a cloth mask were categorised and analysed with the
cloth mask arm.
CRI, clinical respiratory illness; HCWs, healthcare workers; ILI, influenza-like illness; RR, relative risk.
Table 6 A comparison of outcome data for the medical mask arm with medical mask outcomes in previously published RCTs
CRI
N (%)
RR
(95% CI)
ILI
N (%)
RR
(95% CI)
Laboratory-
confirmed
viruses
N (%)
RR
(95% CI)
Vietnam trial 28/580 (4.83) Ref 1/580 (0.17) Ref 19/580 (3.28) Ref
Published RCT
China 1
8
33/492 (6.70) 1.40 (0.85 to 2.26) 3/492 (0.61) 3.53 (0.37 to 33.89) 13/492 (2.64) 0.80 (0.40 to 1.62)
Published RCT
China 2
9
98/572 (17.13) 3.54 (2.37 to 5.31) 4/572 (0.70) 4.06 (0.45 to 36.18) 19/572 (3.32) 1.01 (0.54 to 1.89)
Bold typeface indicates statistically significant.
CRI, Clinical respiratory illness; ILI, influenza-like illness; RCT, randomised clinical trial; RR, relative risk.
8MacIntyre CR, et al.BMJ Open 2015;5:e006577. doi:10.1136/bmjopen-2014-006577
Open Access
grant; however they were not involved in study design, data collection or
analysis. The 3M products were not used in this study.
Contributors CRM was the lead investigator, and responsible for the
conception and design of the trial, obtaining the grant funding, overseeing
the whole study, analysing the data and writing of the report. HS
contributed to overseeing the study, staff training, form/database
development and drafting of the manuscript. TCD was responsible for
overseeing the study, database management, recruitment, training and
revision of the manuscript. NTH was responsible for the implementation
of research and revision of the manuscript. PTN was responsible for the
laboratory testing in Vietnam. AAC contributed to the statistical analysis and
drafting of the manuscript. BR was responsible for the statistical analysis
and revision of the manuscript. DED contributed to the laboratory technical
assistance and revision of the manuscript. QW assisted in comparing the
rates of infection from two previous RCTs conducted in China and revision
of the manuscript.
Funding Funding to conduct this study was received from the Australian
Research Council (ARC) (grant number LP0990749).
Competing interests CRM has held an Australian Research Council Linkage
Grant with 3M as the industry partner, for investigator-driven research. 3M
has also contributed masks and respirators for investigator-driven clinical
trials. CRM has received research grants and laboratory testing as in-kind
support from Pfizer, GSK and Bio-CSL for investigator-driven research. HS
had a NHMRC Australian-based Public Health Training Fellowship at the time
of the study (1012631). She has also received funding from vaccine
manufacturers GSK, bio-CSL and Sanofi Pasteur for investigator-driven
research and presentations. AAC used filtration testing of masks for his PhD
thesis conducted by 3M Australia.
Ethics approval National Institute for Hygiene and Epidemiology (NIHE) (approval
number 05 IRB) and the Human Research Ethics Committee of the University of
New South Wales (UNSW), Australia, (HREC approval number 10306).
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement No additional data are available.
Open Access This is an Open Access article distributed in accordance with
the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license,
which permits others to distribute, remix, adapt, build upon this work non-
commercially, and license their derivative works on different terms, provided
the original work is properly cited and the use is non-commercial. See: http://
creativecommons.org/licenses/by-nc/4.0/
REFERENCES
1. World Health Organization (WHO). Global Alert and Response
(GAR), Pandemic (H1N1) 2009update 76 (cited 27 Apr 2012).
http://www.who.int/csr/don/2009_11_27a/en/index.html
2. World Health Organization (WHO). Human infection with avian
influenza A(H7N9) virusupdate (cited 8 May 2013). http://www.
who.int/csr/don/2013_05_07/en/index.html
3. Bermingham A, Chand MA, Brown CS, et al. Severe respiratory
illness caused by a novel coronavirus, in a patient transferred to the
United Kingdom from the Middle East, September 2012. Euro
Surveill 2012;17:20290.
4. Pollack MP, Pringle C, Madoff LC, et al. Latest outbreak news from
ProMED-mail: novel coronavirusMiddle East. Int J Infect Dis
2013;17:e1434.
5. World Health Organization (WHO). Global Alert and Response
(GAR). Ebola virus disease updatewest Africa 2014 (cited 28 Aug
2014). http://www.who.int/csr/don/2014_08_28_ebola/en/
6. Chughtai AA, Seale H, MacIntyre CR. Use of cloth masks in the
practice of infection controlevidence and policy gaps. Int J Infect
Control 2013;9:112.
7. Quesnel LB. The efficiency of surgical masks of varying design and
composition. Br J Surg 1975;62:93640.
8. MacIntyre CR, Wang Q, Cauchemez S, et al. A cluster
randomized clinical trial comparing fit-tested and non-fit-tested
N95 respirators to medical masks to prevent respiratory virus
infection in health care workers. Influenza Other Respir Viruses
2011;5:1709.
9. MacIntyre CR, Wang Q, Seale H, et al. A randomised clinical trial of
three options for N95 respirators and medical masks in health
workers. Am J Respir Crit Care Med 2013;187:9606.
10. Chughtai AA, MacIntyre CR, Zheng Y, et al. Examining the policies
and guidelines around the use of masks and respirators by
healthcare workers in China, Pakistan and Vietnam. J Infect Prev
2015;16:6874.
11. Chughtai AA, Seale H, Chi Dung T, et al. Current practices and
barriers to the use of facemasks and respirators among
hospital-based health care workers in Vietnam. Am J Infect Control
2015;43:727.
12. Pang X, Zhu Z, Xu F, et al. Evaluation of control measures
implemented in the severe acute respiratory syndrome outbreak in
Beijing. JAMA 2003;290:321521.
13. Yang P, Seale H, MacIntyre C, et al. Mask-wearing and respiratory
infection in healthcare workers in Beijing, China. Braz J Infect Dis
2011;15:1028.
14. Horton R. Medical journals: evidence of bias against the diseases of
poverty. Lancet 2003;361:71213.
15. MacIntyre CR, Chughtai AA. Facemasks for the prevention of
infection in healthcare and community settings. BMJ 2015;350:h694.
16. Chughtai AA, Seale H, MacIntyre CR. Availability, consistency and
evidence-base of policies and guidelines on the use of mask and
respirator to protect hospital health care workers: a global analysis.
BMC Res Notes 2013;6:19.
17. MacIntyre C, Cauchemez S, Dwyer D, et al. Face mask use and
control of respiratory virus transmission in households. Emerg Infect
Dis 2009;15:23341.
18. Buecher C, Mardy S, Wang W, et al. Use of a multiplex PCR/RT-
PCR approach to assess the viral causes of influenza-like illnesses
in Cambodia during three consecutive dry seasons. J Med Virol
2010;82:1762-72 [Epub ahead of print 1 Sep 2010].
19. Higuchi R, Fockler C, Dollinger G, et al. Kinetic PCR analysis: real-
time monitoring of DNA amplification reactions. Biotechnology (NY)
1993;11:102630 [Epub ahead of print 1 Sep 2010].
20. Hummel KB, Lowe L, Bellini WJ, et al. Development of quantitative
gene-specific real-time RT-PCR assays for the detection of measles
virus in clinical specimens. J Virol Methods 2006;132:16673 [Epub
ahead of print 11 Sep 2005].
21. Mackay IM. Real-time PCR in microbiology. Caister Academic
Press, 2007.
22. Wang W, Cavailler P, Ren P, et al. Molecular monitoring of causative
viruses in child acute respiratory infection in endemo-epidemic
situations in Shanghai. J Clin Virol (PASCV) 2010;49:2118.
23. Thi TN, Deback C, Malet I, et al. Rapid determination of antiviral
drug susceptibility of herpes simplex virus types 1 and 2 by real-time
PCR. Antiviral Res 2006;69:1527.
24. Standards Australia Limited/Standards New Zealand. Respiratory
protective devices. Australian/New Zealand Standard. AS/NZS 1716:
2012.
25. Donner A, Klar N. Design and analysis of cluster randomization trials
in health research. London: Oxford University Press Inc, 2000.
26. Campbell MK, Elbourne DR, Altman DG, et al. CONSORT
statement: extension to cluster randomised trials. BMJ
2004;328:7028.
27. Vittinghoff E, Glidden DV, Shiboski SC, et al.Regression methods in
biostatistics. 2nd edn. New York: Springer-Verlag, 2012.
28. StataCorp. Stata 12 base reference manual. College Station, TX:
Stata Press, 2011.
29. Osterholm MT, Moore KA, Kelley NS, et al. Transmission of Ebola
viruses: what we know and what we do not know. mBio 2015;6:
e0013715.
30. Fisher EM, Noti JD, Lindsley WG, et al. Validation and application of
models to predict facemask influenza contamination in healthcare
settings. Risk Anal 2014;34:142334.
31. Li Y, Wong T, Chung J, et al. In vivo protective performance of N95
respirator and surgical facemask. Am J Ind Med 2006;49:105665.
32. Dick EC, Jennings LC, Mink KA, et al. Aerosol transmission of
rhinovirus colds. J Infect Dis 1987;156:4428.
33. Bischoff WE. Transmission route of rhinovirus type 39 in a
monodispersed airborne aerosol. Infect Control Hosp Epidemiol
2010;31:8579.
34. Institute of Medicine (IOM). Reusability of Facemasks During an
Influenza Pandemic: Facing the FluCommittee on the
Development of Reusable Facemasks for Use During an Influenza
Pandemic. National Academy of Sciences, 2006.
35. Center for Disease Control and Prevention and World Health
Organization. Infection control for viral haemorrhagic fevers in the
African health care setting. Atlanta: Centers for Disease Control and
Prevention, 1998:1198.
MacIntyre CR, et al.BMJ Open 2015;5:e006577. doi:10.1136/bmjopen-2014-006577 9
Open Access
36. World Health Organization (WHO). Guidelines for the prevention of
tuberculosis in health care facilities in resource limited settings,
1999.
37. Weaver GH. Droplet infection and its prevention by the face mask.
J Infect Dis 1919;24:21830.
38. MacIntyre CR, Chughtai AA, Seale H, et al.Respiratory
protection for healthcare workers treating Ebola virus disease
(EVD): are facemasks sufficient to meet occupational
health and safety obligations? Int J Nurs Stud 2014;51:
14216.
39. Center for Disease Control and Prevention (CDC). Guidance on
Personal Protective Equipment To Be Used by Healthcare Workers
During Management of Patients with Ebola Virus Disease in U.S.
Hospitals, Including Procedures for Putting On (Donning) and
Removing (Doffing). 2014 (cited 23 Oct 2014). http://www.cdc.gov/
vhf/ebola/hcp/procedures-for-ppe.html
40. World Health Organiszation (WHO). Infection prevention and control
guidance for care of patients in health-care settings, with focus on
Ebola. 2014 (cited 23 Oct 2014). http://www.who.int/csr/resources/
publications/ebola/filovirus_infection_control/en/
10 MacIntyre CR, et al.BMJ Open 2015;5:e006577. doi:10.1136/bmjopen-2014-006577
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... [8] Generally, cloth masks are fabricated from commonly used household fabrics, including cotton, woven, felted, knitted, etc. Cloth masks are not considered medical devices, and randomized clinical trials (RCT) of cloth masks failed to show protection from a two-layered cotton mask. [9] However, evidence suggests that effective cloth masks having high droplet blocking capacity can be designed. [8,10] The filtration efficiency of these masks depends on the type and structure of the fabrics and also the number of utilized cloth layers for the mask. ...
... Cloth masks are reusable but require regular washing, cleaning, or decontamination. Poor quality cloth masks could increase the risk of infection, [9] but well-designed cloth masks can be high-performing as surgical masks. [10b] Daily machine washing keeps cloth masks protective. ...
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Abstract. The use of respiratory protection is one of the measures for the non-specific prophylaxis of coronavirus infection. The wearing of masks is mandatory for the entire population in several countries, including Russia. The object of the study is airport workers who are at an increased risk of infection. They are in contact with many passengers arriving from other countries where mass vaccination has not yet been carried out. The study aims to assess the hygienic prevalence of adverse reactions when using face masks, to identify risk factors for their occurrence. A questionnaire survey and an evaluation of the bacterial contamination of the masks after wearing were carried out. Face sweating under the mask (68.60 %) and feeling short of breath (66.94 %) were the most frequent and pronounced reactions to wearing in comparison with other manifestations (p < 0.001). The more often an adverse reaction occurred, the more apparent it was (r = 0.79–0.95). We found a moderate positive relationship between wearing time and the frequency of facial sweating (r = 0.31). Facial skin reactions were more frequent and pronounced among users of a cotton mask compared with users of neoprene and non-woven masks. An association was found between the frequency and severity of skin manifestations and bacterial contamination of the inner mask’s surface after wearing. A moderate positive relationship was found between the colonies number and wearing time for neoprene and cotton masks (r = 0.33 and 0.46, respectively). The number of colonies increases with the duration of wearing. Factors aggravating adverse reactions’ manifestation: problem skin, young age, moderate and hard work. Recommended: keep the skin clean and well hydrated, change the mask every 2 hours, select the face mask size, fix mask on the face so as not to cause chafing and squeezing of the skin. Keywords: face mask, adverse reactions to face mask wearing, bacterial contamination, survey.
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Introducción. En diciembre de 2019 en Wuhan, China, se presentó un brote de neumonía atípica generado por el virus SARS-CoV-2, el cual es un tipo de coronavirus causante de la enfermedad COVID-19, que se convirtió con el tiempo en una pandemia. En este contexto, el uso de los elementos de protección personal tomó un especial interés, en especial para la atención del trabajo de parto vaginal, dada la confusión en los círculos obstétricos respecto a la mejor forma de proteger al personal sanitario en dichos casos. El objetivo de este artículo de revisión es identificar cuáles son los elementos de protección personal indicados en la atención del parto vaginal y su correcto uso en tiempos de COVID-19. División de temas tratados. Se realizó una revisión narrativa de la literatura accediendo a las bases de datos: PubMed, Medline, Elsevier, Google Académico y sitios web como la Organización Mundial de la salud (OMS), Centros para el Control y la Prevención de Enfermedades (CDC, por sus siglas en inglés) y el Colegio Americano de Obstetras y Ginecólogos (ACOG), entre otros. Se usaron palabras claves como “Infecciones por Coronavirus”, “Parto Normal”, “Protección Personal”, “Personal de Salud”, “Dispositivos de Protección Respiratoria” y “Dispositivos de Protección de los Ojos”. La literatura permitió identificar aspectos introductorios al tema, epidemiología, características generales de los elementos de protección personal, y los elementos específicos para el uso correcto en la atención del parto vaginal. Conclusiones. El trabajo de parto es considerado como un procedimiento generador de aerosoles, por lo que se recomienda principalmente el uso de tapabocas N95 o un respirador que ofrezca mayor protección para personal de salud en la atención del parto vaginal, con el fin de evitar la infección por SARS-CoV-2; sin embargo, se debe insistir en el uso adecuado y completo de los elementos de protección personal como lo son la bata quirúrgica, el gorro, el protector ocular y guantes, independientemente de la sintomatología de la paciente. Introduction. In December 2019, in Wuhan, China, there was an outbreak of atypical pneumonia caused by the SARS-CoV-2 virus, which is a type of coronavirus causative of COVID-19, which overtime became a pandemic. In this context, the use of personal protective equipment is of special interest, especially when providing care in vaginal delivery, due to the confusion in obstetric circles regarding the best way to protect healthcare personnel in these cases. The objective of this review article is to identify which are the personal protective elements indicated for providing care in vaginal birth and their correct use during COVID-19. Division of Covered Topics. A narrative review of the literature was carried out, accessing the following databases: PubMed, Medline, Elsevier, Google Scholar, and websites such as the World Health Organization (WHO), Center for the Control and Prevention of Diseases (CDC), and the American College of Obstetricians and Gynecologists, among others. Keywords such as “Coronavirus Infections”, “Normal Birth,” Personal Protective Elements,” “Healthcare Personnel”, “Respiratory Protective Devices”, and “Eye Protection Devices” were used. The literature allowed us to identify introductory aspects on the matter, epidemiology, general characteristics of personal protective elements, and the specific elements for correct use when providing care in vaginal birth. Conclusions. Labor is considered an aerosol-generating procedure. Therefore, the main recommendation is the use of an N95 mask or a respirator which allows for greater protection for healthcare personnel when assisting vaginal birth, in order to avoid infection due to SARS-CoV-2. However, there must be an adequate and complete use of personal protective equipment, such as surgical gowns, hats, eye protection and gloves, regardless of the patient’s symptomatology. Introdução. Em dezembro de 2019 em Wuhan, na China, houve um surto de pneumonia atípica gerada pelo vírus SARS-CoV-2, que é um tipo de coronavírus que causa a doença COVID-19, que, com o tempo, acabou se tornando uma pandemia. Nesse contexto, o uso de elementos de proteção individual tornou-se de particular interesse, especialmente para a assistência do parto vaginal, dada a confusão nos círculos obstétricos quanto à melhor forma de proteger os profissionais da saúde nesses casos. O objetivo deste artigo de revisão é identificar os elementos de proteção individual indicados na assistência do parto vaginal e seu uso correto em tempos de COVID-19. Divisão de tópicos abordados. Foi realizada uma revisão narrativa da literatura acessando as seguintes bases de dados: PubMed, Medline, Elsevier, Google Scholar e sites como a Organização Mundial da Saúde (OMS), Centros de Controle e Prevenção de Doenças (CDC, na sigla em inglês) e o Colégio Americano de Obstetras e Ginecologistas (ACOG), entre outros. Foram utilizadas palavras-chave como “Infecções por Coronavírus”, “Parto Normal”, “Proteção Pessoal”, “Pessoal de Saúde”, “Dispositivos de Proteção Respiratória” e “Dispositivos de Proteção Ocular”. A literatura permitiu identificar aspectos introdutórios ao tema, epidemiologia, características gerais dos elementos de proteção individual e elementos específicos para o uso correto na assistência do parto vaginal. Conclusões. O trabalho de parto é considerado um procedimento gerador de aerossóis, portanto, recomenda-se principalmente o uso de máscaras N95 ou um respirador que ofereça maior proteção para os profissionais de saúde na assistência do parto vaginal, a fim de evitar a infecção pelo SARS-CoV-2; no entanto, deve-se insistir no uso adequado e completo de elementos de proteção individual, como bata cirúrgica, touca, protetor ocular e luvas, independentemente dos sintomas do paciente.
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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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Title: Respiratory protection for healthcare workers treatingebola virus disease (evd): are facemasks sufficient to meetoccupational health and safety obligations?Author: C. Raina MacIntyre Abrar Ahmad Chughtai HollySeale Guy A Richards Patricia M DavidsonPII: S0020-7489(14)00234-XDOI: http://dx.doi.org/doi:10.1016/j.ijnurstu.2014.09.002Reference: NS 2443To appear in:Please cite this article as: MacIntyre, C.R., Chughtai, A.A., Seale, H.,Richards, G.A., Davidson, P.M.,Respiratory protection for healthcare workerstreating ebola virus disease (evd): are facemasks sufficient to meet occupationalhealth and safety obligations?,
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Facemasks are part of the hierarchy of interventions used to reduce the transmission of respiratory pathogens by providing a barrier. Two types of facemasks used by healthcare workers are N95 filtering facepiece respirators (FFRs) and surgical masks (SMs). These can become contaminated with respiratory pathogens during use, thus serving as potential sources for transmission. However, because of the lack of field studies, the hazard associated with pathogen-exposed facemasks is unknown. A mathematical model was used to calculate the potential influenza contamination of facemasks from aerosol sources in various exposure scenarios. The aerosol model was validated with data from previous laboratory studies using facemasks mounted on headforms in a simulated healthcare room. The model was then used to estimate facemask contamination levels in three scenarios generated with input parameters from the literature. A second model estimated facemask contamination from a cough. It was determined that contamination levels from a single cough (≈19 viruses) were much less than likely levels from aerosols (4,473 viruses on FFRs and 3,476 viruses on SMs). For aerosol contamination, a range of input values from the literature resulted in wide variation in estimated facemask contamination levels (13–202,549 viruses), depending on the values selected. Overall, these models and estimates for facemask contamination levels can be used to inform infection control practice and research related to the development of better facemasks, to characterize airborne contamination levels, and to assist in assessment of risk from reaerosolization and fomite transfer because of handling and reuse of contaminated facemasks.
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Cloth masks are commonly used in low and middle income countries. It is generally believed that the primary purpose of cloth masks is to prevent spread of infections from the wearer. However, historical evidence shows that they had been used in the past for protection of health care workers (HCWs) from respiratory infections. Currently there is a lack of evidence on the efficacy of cloth masks. In this paper, we examined the evidence on the efficacy of cloth masks and discuss the use of cloth masks as a mode of protection from infections in HCWs. We also discuss various methods to improve the effectiveness of cloth masks; for example; type of fabric, masks design and face fit. Further research is required to validate the use of cloth masks in HCWs for prevention of respiratory infections.
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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.