New England Journal of
Medicine
Editor’s Note: This article was published on April 1, 2020, at
NEJM.org.
Universal Masking
in Hospitals in the Covid-19 Era
List of authors.
·
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.
As the SARS-CoV-2
pandemic continues to explode, hospital systems are scrambling to intensify
their measures for protecting patients and health care workers from the virus.
An increasing number of frontline providers are wondering whether this effort
should include universal use of masks by all health care workers. Universal
masking is already 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 offers little, if any, protection from
infection. Public health authorities define a significant exposure to Covid-19
as face-to-face contact within 6 feet with a patient with symptomatic Covid-19
that is sustained for at least a few minutes (and some say more than 10 minutes
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
widespread masking is a reflexive reaction to anxiety over the pandemic.
may be different,
however, in health care settings. First and foremost, a mask is a core
component of the personal protective equipment (PPE) clinicians need when
caring for symptomatic 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 patients. 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 slightly, however, since it does not provide protection
from droplets that may enter the eyes or from fomites on the patient or in the
environment that providers may pick up on their hands and carry to their mucous
membranes (particularly given the concern that mask wearers may have an
increased tendency to touch their faces).
More compelling is the
possibility that wearing a mask may reduce the likelihood of transmission from
asymptomatic and minimally symptomatic health care workers with Covid-19 to
other providers and patients. This concern increases as Covid-19 becomes more
widespread in the community. We face a constant risk that a health care worker with
early infection may bring the virus into our facilities and transmit it to
others. Transmission from people with asymptomatic infection has been well
documented, although it is unclear to what extent 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 allergies,
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 symptoms that were subsequently
diagnosed as Covid-19. These cases have led to large numbers of our patients
and staff members being exposed to the virus and a handful of potentially
linked infections in health care workers. Masking all providers might limit
transmission from these sources by stopping 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 it’s not
accompanied 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 diverts attention from implementing 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;
rescreening all admitted patients daily for signs and symptoms of Covid-19 in
case an infection was incubating on admission or they were exposed to the virus
in the hospital; having a low threshold for testing patients with even mild
symptoms potentially attributable to a viral respiratory infection (this
includes patients with pneumonia, given that a third or more of pneumonias are
caused by viruses rather than bacteria); requiring 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 minimally 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
assessing the spread of infection in Wuhan have noted the importance of
undiagnosed infections in fueling the spread of Covid-19 while also
acknowledging that the transmission 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
paradoxically improve inventory control by reducing one-time uses and
facilitating centralized workflows for allocating masks without risk assessments
at the individual-employee level.
There may be
additional benefits to broad masking policies that extend beyond their
technical contribution to reducing pathogen transmission. Masks are visible
reminders of an otherwise invisible yet widely prevalent pathogen and may
remind people of the importance 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 hospitals. 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, particularly in
light of the worldwide mask shortage, but it is difficult to get clinicians to
hear this message in the heat of the current crisis. Expanded masking
protocols’ greatest contribution may be to reduce the transmission of anxiety,
over and above whatever role they may play in reducing transmission of
Covid-19. The potential value of universal masking in giving health care
workers the confidence to absorb and implement the more foundational
infection-prevention practices described above may be its greatest
contribution.
Disclosure forms provided by the authors
are available at NEJM.org.
This article was
published on April 1, 2020, at NEJM.org.
Author Affiliations
From the Department of
Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care
Institute (M.K.), Brigham and Women’s 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 Division of Infectious Diseases, Massachusetts General Hospital (E.S.S.) —
all in Boston.
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