re-think
Perspective
T h e N EW ENGL A N D JOU R NA L o f M EDICI N E
May 21, 2020
n engl j med 382;21 nejm.org May 21, 2020 e63(1)
As the SARS-CoV-2 pandemic continues to explode, hospital systems are scrambling to intensify their measures for protecting pa-
tients and health care workers from the virus. An
increasing number of frontline
providers are wondering whether
this effort should include univer-
sal use of masks by all health care
workers. Universal masking is al-
ready standard practice in Hong
Kong, Singapore, and other parts
of Asia and has recently been
adopted by a handful of U.S.
hospitals.
We know that wearing a mask
outside health care facilities of-
fers little, if any, protection from
infection. Public health authori-
ties define a significant exposure
to Covid-19 as face-to-face contact
within 6 feet with a patient with
symptomatic Covid-19 that is sus-
tained for at least a few minutes
(and some say more than 10 min-
utes or even 30 minutes). The
chance of catching Covid-19 from
a passing interaction in a public
space is therefore minimal. In
many cases, the desire for wide-
spread masking is a reflexive re-
action to anxiety over the pan-
demic.
The calculus may be different,
however, in health care settings.
First and foremost, a mask is a
core component of the personal
protective equipment (PPE) clini-
cians need when caring for symp-
tomatic patients with respiratory
viral infections, in conjunction with
gown, gloves, and eye protection.
Masking in this context is already
part of routine operations for most
hospitals. What is less clear is
whether a mask offers any further
protection in health care settings
in which the wearer has no direct
interactions with symptomatic pa-
tients. There are two scenarios
in which there may be possible
benefits.
The first is during the care of
a patient with unrecognized
Covid-19. A mask alone in this
setting will reduce risk only slight-
ly, however, since it does not pro-
vide protection from droplets that
may enter the eyes or from fomites
on the patient or in the environ-
ment that providers may pick up
on their hands and carry to their
mucous membranes (particularly
given the concern that mask wear-
ers may have an increased ten-
dency to touch their faces).
More compelling is the possi-
bility that wearing a mask may
reduce the likelihood of transmis-
sion from asymptomatic and min-
imally symptomatic health care
workers with Covid-19 to other
providers and patients. This con-
cern increases as Covid-19 be-
comes more widespread in the
community. We face a constant
risk that a health care worker with
Universal Masking in Hospitals in the Covid-19 Era
Michael Klompas, M.D., M.P.H., Charles A. Morris, M.D., M.P.H., Julia Sinclair, M.B.A.,
Madelyn Pearson, D.N.P., R.N., and Erica S. Shenoy, M.D., Ph.D.
Universal Masking in Hospitals in the Covid-19 Era
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P E R S P E C T I V E
e63(2)
Universal Masking in Hospitals in the Covid-19 Era
n engl j med 382;21 nejm.org May 21, 2020
early infection may bring the virus
into our facilities and transmit it
to others. Transmission from peo-
ple with asymptomatic infection
has been well documented, al-
though it is unclear to what ex-
tent such transmission contributes
to the overall spread of infection.1-3
More insidious may be the
health care worker who comes to
work with mild and ambiguous
symptoms, such as fatigue or
muscle aches, or a scratchy throat
and mild nasal congestion, that
they attribute to working long
hours or stress or seasonal aller-
gies, rather than recognizing
that they may have early or mild
Covid-19. In our hospitals, we have
already seen a number of instances
in which staff members either
came to work well but developed
symptoms of Covid-19 partway
through their shifts or worked
with mild and ambiguous symp-
toms that were subsequently di-
agnosed as Covid-19. These cases
have led to large numbers of our
patients and staff members being
exposed to the virus and a hand-
ful of potentially linked infections
in health care workers. Masking
all providers might limit transmis-
sion from these sources by stop-
ping asymptomatic and minimally
symptomatic health care workers
from spreading virus-laden oral
and nasal droplets.
What is clear, however, is that
universal masking alone is not a
panacea. A mask will not protect
providers caring for a patient with
active Covid-19 if its not accom-
panied by meticulous hand hygiene,
eye protection, gloves, and a gown.
A mask alone will not prevent
health care workers with early
Covid-19 from contaminating their
hands and spreading the virus to
patients and colleagues. Focusing
on universal masking alone may,
paradoxically, lead to more
transmission of Covid-19 if it di-
verts attention from implement-
ing more fundamental infection-
control measures.
Such measures include vigorous
screening of all patients coming to
a facility for symptoms of Covid-19
and immediately getting them
masked and into a room; early
implementation of contact and
droplet precautions, including eye
protection, for all symptomatic
patients and erring on the side of
caution when in doubt; rescreen-
ing all admitted patients daily for
signs and symptoms of Covid-19
in case an infection was incubat-
ing on admission or they were
exposed to the virus in the hos-
pital; having a low threshold for
testing patients with even mild
symptoms potentially attributable
to a viral respiratory infection
(this includes patients with pneu-
monia, given that a third or more
of pneumonias are caused by vi-
ruses rather than bacteria); requir-
ing employees to attest that they
have no symptoms before starting
work each day; being attentive to
physical distancing between staff
members in all settings (including
potentially neglected settings such
as elevators, hospital shuttle buses,
clinical rounds, and work rooms);
restricting and screening visitors;
and increasing the frequency and
reliability of hand hygiene.
The extent of marginal benefit
of universal masking over and
above these foundational measures
is debatable. It depends on the
prevalence of health care workers
with asymptomatic and minimal-
ly symptomatic infections as well
as the relative contribution of
this population to the spread of
infection. It is informative, in
this regard, that the prevalence of
Covid-19 among asymptomatic
evacuees from Wuhan during the
height of the epidemic there was
only 1 to 3%.4,5 Modelers assess-
ing the spread of infection in Wu-
han have noted the importance of
undiagnosed infections in fueling
the spread of Covid-19 while also
acknowledging that the transmis-
sion risk from this population is
likely to be lower than the risk of
spread from symptomatic patients.3
And then the potential benefits
of universal masking need to be
balanced against the future risk
of running out of masks and
thereby exposing clinicians to the
much greater risk of caring for
symptomatic patients without a
mask. Providing each health care
worker with one mask per day for
extended use, however, may para-
doxically improve inventory con-
trol by reducing one-time uses
and facilitating centralized work-
flows for allocating masks with-
out risk assessments at the indi-
vidual-employee level.
There may be additional ben-
efits to broad masking policies
that extend beyond their technical
contribution to reducing pathogen
transmission. Masks are visible re-
minders of an otherwise invisible
yet widely prevalent pathogen and
may remind people of the impor-
tance of social distancing and
other infection-control measures.
It is also clear that masks serve
symbolic roles. Masks are not only
tools, they are also talismans that
may help increase health care
workers perceived sense of safety,
well-being, and trust in their hos-
pitals. Although such reactions
may not be strictly logical, we are
all subject to fear and anxiety,
especially during times of crisis.
One might argue that fear and
anxiety are better countered with
data and education than with a
marginally beneficial mask, par-
The New England Journal of Medicine
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P E R S P E C T I V E
e63(3)
Universal Masking in Hospitals in the Covid-19 Era
n engl j med 382;21 nejm.org May 21, 2020
ticularly in light of the worldwide
mask shortage, but it is difficult
to get clinicians to hear this mes-
sage in the heat of the current cri-
sis. Expanded masking protocols
greatest contribution may be to
reduce the transmission of anxi-
ety, over and above whatever role
they may play in reducing trans-
mission of Covid-19. The poten-
tial value of universal masking in
giving health care workers the
confidence to absorb and imple-
ment the more foundational in-
fection-prevention practices de-
scribed above may be its greatest
contribution.
Disclosure forms provided by the au-
thors are available at NEJM.org.
From the Department of Population Medi-
cine, Harvard Medical School and Harvard
Pilgrim Health Care Institute (M.K.), Brigham
and Womens Hospital (M.K., C.A.M., J.S.,
M.P.), Harvard Medical School (M.K., C.A.M.,
E.S.S.), and the Infection Control Unit and Di-
vision of Infectious Diseases, Massachusetts
General Hospital (E.S.S.) all in Boston.
This article was published on April 1, 2020,
at NEJM.org.
1. Rothe C, Schunk M, Sothmann P, et al.
Transmission of 2019-nCoV infection from
an asymptomatic contact in Germany. N Engl
J Med 2020; 382: 970-1.
2. Bai Y, Yao L, Wei T, et al. Presumed asymp-
tomatic carrier transmission of COVID-19.
JAMA 2020 February 21 (Epub ahead of print).
3. Li R, Pei S, Chen B, et al. Substantial un-
documented infection facilitates the rapid dis-
semination of novel coronavirus (SARS-CoV2).
Science 2020 March 16 (Epub ahead of print).
4. Hoehl S, Rabenau H, Berger A, et al.
Evidence of SARS-CoV-2 infection in return-
ing travelers from Wuhan, China. N Engl J
Med 2020; 382: 1278-80.
5. Ng O-T, Marimuthu K, Chia P-Y, et al.
SARS-CoV-2 infection among travelers re-
turning from Wuhan, China. N Engl J Med
2020; 382:1476-8.
DOI: 10.1056/NEJMp2006372
Copyright 2020 Massachusetts Medical Society.Universal Masking in Hospitals in the Covid-19 Era
The New England Journal of Medicine
Downloaded from nejm.org on July 31, 2020. For personal use only. No other uses without permission.
Copyright 2020 Massachusetts Medical Society. All rights reserved. Comment
434 www.thelancet.com/respiratory Vol 8 May 2020
Rational use of face masks in the COVID-19 pandemic
Since the outbreak of severe acute respiratory syndrome
coronavirus 2 (SARS-CoV-2), the virus that caused
coronavirus disease 2019 (COVID-19), the use of face
masks has become ubiquitous in China and other Asian
countries such as South Korea and Japan. Some provinces
and municipalities in China have enforced compulsory
face mask policies in public areas; however, Chinas
national guideline has adopted a risk-based approach
in offering recommendations for using face masks
among health-care workers and the general public. We
compared face mask use recommendations by different
health authorities (panel). Despite the consistency in
Published Online
March 20, 2020
https://doi.org/10.1016/
S2213-2600(20)30134-X
specific contraindication, and can be initiated along with
the interventions already described.
For persistent refractory hypoxaemia even with prone
positioning, neuromuscular blockade, and efforts to
optimise positive end-expiratory pressure therapy, there
are additional options. Inhaled 520 ppm NO might
improve oxygenation. Insertion of an oesophageal
balloon to measure transpulmonary pressures to set
an optimal positive end-expiratory pressure can be
considered in patients with moderate-to-severe obesity,
although a 2019 trial in patients with ARDS did not
show the benefit of this procedure in most patients.7
Fluid management is important to consider as a
measure to reduce pulmonary oedema.8 In the absence
of shock, fluid conservative therapy is recommended
to achieve a negative fluid balance of 05 to 10 L
per day. In the presence of shock, fluid balance might be
achieved with renal replacement therapy, especially
if there is associated acute kidney injury and oliguria.
Antibiotics should be considered since secondary
bacterial infections have been reported in patients with
COVID-19.9 Glucocorticoids should be avoided in view
of the evidence that they can be harmful in cases of viral
pneumonia and ARDS from influenza.10 Rescue therapy
with high-dose vitamin C can also be considered.11
Finally, ECMO should be considered using the inclusion
and exclusion criteria of the EOLIA trial.3
Since treatment of severe ARDS from COVID-19
is an ongoing challenge, it is important to learn
from the patients who have been treated to gain an
understanding of the diseases epidemiology, biological
mechanisms, and the effects of new pharmacological
interventions. Currently, there are some research groups
working to coordinate and disseminate key information,
including information on patients who have been
treated with ECMO for COVID-19, although an accurate
estimate of the number of such patients is not currently
available. The Extracorporeal Life Support Organization
is an international non-profit consortium that plans to
maintain a registry of patients to facilitate an improved
understanding of how ECMO is being used for patients
with COVID-19.
MAM reports grants from the National Institutes of Healththe National
Heart, Lung and Blood Institute, the US Food and Drug Administration, the US
Department of Defense, Bayer Pharmaceuticals, Genentech-Roche, and
personal fees from Gen1e Life Sciences, outside of the submitted work. JMA
has done been part of the electronic medical records committee of the Society
of Critical Care Medicine, outside of the submitted work. JEG declares no
competing interests.
*Michael A Matthay, J Matthew Aldrich, Jeffrey E Gotts
[emailprotected]
Department of Medicine, Department of Anesthesia (MAM, JMA, JEG), and
Cardiovascular Research Institute (MAM), The University of California,
San Francisco, CA 94158, USA
1 Ramanathan K, Antognini D, Combes A, et al. Planning and provision of
ECMO services for severe ARDS during the COVID-19 pandemic and other
outbreaks of emerging infectious diseases. Lancet Respir Med 2020; published
online March 20. https://doi.org/10.1016/S2213-2600(20)30121-1.
2 Fielding-Singh V, Matthay MA, Calfee CS. Beyond low tidal volume
ventilation: treatment adjuncts for severe respiratory failure in acute
respiratory distress syndrome. Crit Care Med 2018; 46: 182031.
3 Combes A, Hajage D, Capellier G, et al. Extracorporeal membrane
oxygenation for severe acute respiratory distress syndrome. N Engl J Med
2018; 378: 196575.
4 Frat J-P, Thille AW, Mercat A, et al. High-flow oxygen through nasal cannula
in acute hypoxemic respiratory failure. N Engl J Med 2015; 372: 218596.
5 WHO. Infection prevention and control during health care when novel
coronavirus (nCoV) infection is suspected: interim guidance. 2020.
https://apps.who.int/iris/rest/bitstreams/1266296/retrieve (accessed
March 13, 2020).
6 Sahetya SK, Brower RG. Lung recruitment and titrated PEEP in moderate to
severe ARDS: is the door closing on the open lung? JAMA 2017; 318: 132729.
7 Beitler JR, Sarge T, Banner-Goodspeed VM, et al. Effect of titrating positive
end-expiratory pressure (PEEP) with an esophageal pressure-guided
strategy vs an empirical high PEEP-FiO2 strategy on death and days free
from mechanical ventilation among patients with acute respiratory
distress syndrome: a randomized clinical trial. JAMA 2019; 321: 84657.
8 Wiedemann HP, Wheeler AP, Bernard GR, et al. Comparison of two fluid-
management strategies in acute lung injury. N Engl J Med 2006;
354: 256475.
9 Huang C, Wang Y, Li Y, et al. Clinical features of patients infected with 2019
novel coronavirus in Wuhan, China. Lancet 2020; 395: 497506.
10 Ni Y-N, Chen G, Sun J, Liang B-M, Liang Z-A. The effect of corticosteroids on
mortality of patients with influenza pneumonia: a systematic review and
meta-analysis. Critical Care 2019; 23: 99.
11 Fowler AA, Truwit JD, Hite RD, et al. Effect of vitamin C infusion on organ
failure and biomarkers of inflammation and vascular injury in patients with
sepsis and severe acute respiratory failure: the CITRIS-ALI randomized
clinical trial. JAMA 2019; 322: 126170.
For the Extracorporeal Life
Support Organization see
https://www.elso.org/Home.
aspx
https://www.elso.org/Home.aspx
https://www.elso.org/Home.aspx
https://www.elso.org/Home.aspx
http://crossmark.crossref.org/dialog/?doi=10.1016/S2213-2600(20)30134-X&domain=pdf
Comment
www.thelancet.com/respiratory Vol 8 May 2020 435
the recommendation that symptomatic individuals and
those in health-care settings should use face masks,
discrepancies were observed in the general public and
community settings.18 For example, the US Surgeon
General advised against buying masks for use by healthy
people. One important reason to discourage widespread
use of face masks is to preserve limited supplies for
professional use in health-care settings. Universal face
mask use in the community has also been discouraged
with the argument that face masks provide no effective
protection against coronavirus infection.
However, there is an essential distinction between
absence of evidence and evidence of absence. Evidence
that face masks can provide effective protection against
respiratory infections in the community is scarce, as
acknowledged in recommendations from the UK and
Germany.7,8 However, face masks are widely used by
medical workers as part of droplet precautions when
caring for patients with respiratory infections. It would
be reasonable to suggest vulnerable individuals avoid
crowded areas and use surgical face masks rationally
when exposed to high-risk areas. As evidence suggests
COVID-19 could be transmitted before symptom onset,
community transmission might be reduced if everyone,
including people who have been infected but are
asymptomatic and contagious, wear face masks.
Recommendations on face masks vary across countries
and we have seen that the use of masks increases
substantially once local epidemics begin, including the
use of N95 respirators (without any other protective
equipment) in community settings. This increase in
use of face masks by the general public exacerbates
the global supply shortage of face masks, with prices
soaring,9 and risks supply constraints to frontline health-
care professionals. As a response, a few countries (eg,
Germany and South Korea) banned exportation of face
masks to prioritise local demand.10 WHO called for a 40%
increase in the production of protective equipment,
including face masks.9 Meanwhile, health authorities
should optimise face mask distribution to prioritise
Panel: Recommendations on face mask use in community settings
WHO1
If you are healthy, you only need to wear a mask if you are
taking care of a person with suspected SARS-CoV-2 infection.
China2
People at moderate risk* of infection: surgical or disposable
mask for medical use.
People at low risk of infection: disposable mask for medical
use.
People at very low risk of infection: do not have to wear a
mask or can wear non-medical mask (such as cloth mask).
Hong Kong3
Surgical masks can prevent transmission of respiratory
viruses from people who are ill. It is essential for people who
are symptomatic (even if they have mild symptoms) to wear
a surgical mask.
Wear a surgical mask when taking public transport or
staying in crowded places. It is important to wear a mask
properly and practice good hand hygiene before wearing
and after removing a mask.
Singapore4
Wear a mask if you have respiratory symptoms, such as a
cough or runny nose.
Japan5
The effectiveness of wearing a face mask to protect yourself
from contracting viruses is thought to be limited. If you
wear a face mask in confined, badly ventilated spaces, it
might help avoid catching droplets emitted from others but
if you are in an open-air environment, the use of face mask
is not very efficient.
USA6
Centers for Disease Control and Prevention does not
recommend that people who are well wear a face mask
(including respirators) to protect themselves from
respiratory diseases, including COVID-19.
US Surgeon General urged people on Twitter to stop buying
face masks.
UK7
Face masks play a very important role in places such as
hospitals, but there is very little evidence of widespread
benefit for members of the public.
Germany8
There is not enough evidence to prove that wearing a surgical
mask significantly reduces a healthy persons risk of becoming
infected while wearing it. According to WHO, wearing a mask
in situations where it is not recommended to do so can create
a false sense of security because it might lead to neglecting
fundamental hygiene measures, such as proper hand hygiene.
*People at moderate risk of infection include those working in areas of high population
density (eg, hospitals, train stations), those have been or live with somebody who is
quarantined, and administrative staff, police, security, and couriers whose work is related to
COVID-19. People at low risk of infection include those staying in areas of high population
density (eg, supermarket, shopping mall), who work indoors, who seek health care in
medical institutions (other than fever clinics), and gatherings of children aged 36 years
and school students. People at very low risk of infection include those who mostly stay at
home, who do outdoor activities, and who work or study in well-ventilated areas.
Sp
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y
Comment
436 www.thelancet.com/respiratory Vol 8 May 2020
the needs of frontline health-care workers and the
most vulnerable populations in communities who are
more susceptible to infection and mortality if infected,
including older adults (particularly those older than
65 years) and people with underlying health conditions.
People in some regions (eg, Thailand, China, and
Japan) opted for makeshift alternatives or repeated
usage of disposable surgical masks. Notably, improper
use of face masks, such as not changing disposable
masks, could jeopardise the protective effect and even
increase the risk of infection.
Consideration should also be given to variations in
societal and cultural paradigms of mask usage. The
contrast between face mask use as hygienic practice
(ie, in many Asian countries) or as something only
people who are unwell do (ie, in European and North
American countries) has induced stigmatisation and
racial aggravations, for which further public education is
needed. One advantage of universal use of face masks is
that it prevents discrimination of individuals who wear
masks when unwell because everybody is wearing a mask.
It is time for governments and public health agencies
to make rational recommendations on appropriate face
mask use to complement their recommendations on
other preventive measures, such as hand hygiene. WHO
currently recommends that people should wear face
masks if they have respiratory symptoms or if they are
caring for somebody with symptoms. Perhaps it would
also be rational to recommend that people in quarantine
wear face masks if they need to leave home for any reason,
to prevent potential asymptomatic or presymptomatic
transmission. In addition, vulnerable populations,
such as older adults and those with underlying medical
conditions, should wear face masks if available. Universal
use of face masks could be considered if supplies permit.
In parallel, urgent research on the duration of protection
of face masks, the measures to prolong life of disposable
masks, and the invention on reusable masks should be
encouraged. Taiwan had the foresight to create a large
stockpile of face masks; other countries or regions might
now consider this as part of future pandemic plans.
We declare no competing interests.
Editorial note: the Lancet Group takes a neutral position with respect to
territorial claims in published maps and institutional affiliations.
*Shuo Feng, Chen Shen, Nan Xia, Wei Song,
Mengzhen Fan, Benjamin J Cowling
[emailprotected]
Contributed equally.
Oxford Vaccine Group, University of Oxford, Oxford, OX3 7LE, UK (SF);
Department of Epidemiology and Biostatistics, Imperial College London, London,
UK (CS); School of Public Health, Li Ka Shing Faculty of Medicine, The University
of Hong Kong, Pokfulam, Hong Kong, Special Administrative Region, China (NX,
BJC); Department of Chemistry, University of Oxford, Oxford, UK (MF); and
Department of Economics and Related Studies, University of York, York, UK (WS)
1 WHO. Coronavirus disease (COVID-19) advice for the public: when and how
to use masks. 2020. https://www.who.int/emergencies/diseases/novel-
coronavirus-2019/advice-for-public/when-and-how-to-use-masks
(accessed March 17, 2020).
2 State Council, China. Guidelines for the selection and use of different types
of masks for preventing new coronavirus infection in different populations
2020 (in Chinese). Feb 5, 2020. http://www.gov.cn/xinwen/2020-02/05/
content_5474774.htm (accessed March 17, 2020).
3 The Department of Health, Hong Kong. Guidelines on prevention of
coronavirus disease 2019 (COVID-19) for the general public. Mar 13, 2020.
https://www.chp.gov.hk/files/pdf/nid_guideline_general_public_en.pdf
(accessed March 17, 2020).
4 Ministry of Health, Singapore. Updates on COVID-19 (coronavirus disease
2019) local situation. https://www.moh.gov.sg/covid-19 (accessed
March 17, 2020).
5 Ministry of Health, Labour and Wellfare, Japan. Q & A on coronavirus 2019
(COVID-19): when should I wear a facemask? 2020. https://www.mhlw.
go.jp/stf/seisakunitsuite/bunya/kenkou_iryou/dengue_fever_qa_00014.
html (accessed March 17, 2020).
6 CDC. Coronavirus Disease 2019 (COVID-19): steps to prevent illness.
https://www.cdc.gov/coronavirus/2019-ncov/about/prevention-
treatment.html (accessed March 17, 2020).
7 National Health Service. Are face masks useful for preventing coronavirus?
2020. https://www.nhs.uk/conditions/coronavirus-covid-19/common-
questions/ (accessed March 5, 2020).
8 Federal Ministry of Health, Germany. Daily updates on the coronavirus: is
wearing a surgical mask, as protection against acute respiratory infections,
useful for members of the general public? 2020. https://www.
bundesgesundheitsministerium.de/en/press/2020/coronavirus.html
(accessed March 5, 2020).
9 WHO. Shortage of personal protective equipment endangering health
workers worldwide. March 3, 2020. https://www.who.int/news-room/
detail/03-03-2020-shortage-of-personal-protective-equipment-
endangering-health-workers-worldwide (accessed March 17, 2020).
10 Tsang A. EU seeks solidarity as nations restrict medical exports.
March 7, 2020. https://www.nytimes.com/2020/03/07/business/eu-
exports-medical-equipment.html (accessed March 17, 2020).
Coronavirus disease 2019 (COVID-19), caused
by the novel severe acute respiratory syndrome
coronavirus 2 (SARS-CoV-2), is an acute respiratory
disease that can lead to respiratory failure and death.1
Previous epidemics of novel coronavirus diseases, such
as severe acute respiratory syndrome (SARS) and Middle
Do chronic respiratory diseases or their treatment affect the
risk of SARS-CoV-2 infection?
Published Online
April 3, 2020
https://doi.org/10.1016/
S2213-2600(20)30167-3
Rational use of face masks in the COVID-19 pandemic
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