The New England journal of medicine
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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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-
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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
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