Noi continuiamo a seguire le regole e a indossare la mascherina secondo le norme imposte da tutti i DCPM. Tuttavia, un articolo del 20 aprile del The New England Journal of Medicine racconta un'altra storia, ossia che la mascherina, usata da sola senza altra precauzione, come pulizia delle mani, guanti eccetera, non serve ad altro che a placare l'ansia. Sarebbe insomma essenzialmente un talismano. Le sottolineature sono mie. Purtroppo non ho tempo di tradurlo, e comunque, buona lettura!
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.
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) 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%.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. 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.
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