Fear of
coronavirus infection has led to a massive increase in sales of surgical
face masks and respirators. Many health care facilities are now
struggling to obtain the supplies needed to protect health care workers
and patients
Health experts
are issuing public statements saying the masks won’t protect healthy
people against infection and, according to the FDA, the “immediate
health risk from COVID-19 is considered low,” so face masks are
unwarranted for public use
While the
evidence is conflicting, some studies suggest healthy people do limit
their chances of infection if wearing a face mask, especially properly
fitted N95 or N100 respirators
A 2009 study
found use of face masks in households was ineffective due to low
adherence, not because they don’t prevent the transmission of illness.
In fact, were more people to wear masks, influenza-like infection rates
would probably be lower
A 2015
meta-analysis found that in 8 of 9 trials, use of face masks in
community settings prevented infection in healthy people when used in
isolation or in combination with hand hygiene, when used early and
consistently
With 101,606 reported COVID-19 cases across 96 countries and territories as of March 6, 2020,1
and no known cure, people are seeking ways to protect themselves
against infection. Logically, many are resorting to wearing face masks
when venturing out in public.
However, as face masks are becoming harder to come by, health
experts are issuing public statements saying the masks won't protect
healthy people against infection. Is that true? Or is it a ploy to
ensure an adequate supply for health care workers? As reported in a
March 4, 2020, Time article:2
"'It seems kind of intuitively obvious that if you put something
— whether it's a scarf or a mask — in front of your nose and mouth,
that will filter out some of these viruses that are floating around out
there,' says Dr. William Schaffner, professor of medicine in the
division of infectious diseases at Vanderbilt University.
The only problem: that's not effective against respiratory
illnesses like the flu and COVID-19. If it were, 'the CDC would have
recommended it years ago,' he says. 'It doesn't, because it makes
science-based recommendations.'"
Do Masks Only Protect Health Care Workers?
According to the U.S. Centers for Disease Control and Prevention,
surgical masks are not designed to provide protection against airborne pathogens and are not considered respiratory protection. They're only designed to prevent large-particle droplets (which may contain pathogens) from reaching your mouth and nose.3,4
Part of the problem is that these kinds of masks won't form a seal
around your face. Most people also have a tendency to touch their face a
lot, thus depositing pathogens from their hands to their face anyway.
According to U.S. Surgeon General Dr. Jerome Adams, wearing a mask
may actually increase your risk of infection, as most people will touch
their face even more frequently when wearing one.5 The CDC only recommends surgical masks for:
People who are symptomatic, as the mask will inhibit the spread of the virus if you cough or sneeze into the mask
Caregivers for infected patients
Mayo Clinic infectious diseases specialist Dr. Nipunie Rajapakse explains:6
"The current recommendations regarding masks are that if you
yourself are sick with fever and cough, you can wear a surgical mask to
prevent transmission to other people.
If you are healthy, there is not thought to be any additional
benefit to wearing a mask yourself because the mask is not airtight and
does not necessarily prevent breathing in of these viral particles,
which are very tiny."
What About N95 Respirators?
The CDC also does not recommend that the general public wear N95
respirators, which are designed to be tight-fitting and capable of
filtering out at least 95% of much smaller (0.3 micron in size)
airborne particles. According to the U.S. Food and Drug Administration:7
"For the general American public, there is no added
health benefit to wear a respiratory protective device (such as an N95
respirator), and the immediate health risk from COVID-19 is considered
low."
You wouldn't think the health risk from COVID-19 was "considered
low" by looking at or listening to the news though. Perhaps journalists
didn't get the memo?
Either way, it strikes many as odd that facemasks and N95
respirators are universally considered key instruments for infection
control in health care settings, yet the general public is now told
they won't protect against respiratory diseases such as COVID-19.
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The Respirator Fit Test
One reason cited for why the public should not use N95 respirator
masks either, even though they protect against airborne pathogens, is
because they require fit testing to ensure a tight seal around the
face.8
However, according to the CDC's fit test Q & A document,9
this is a relatively simple affair. The qualitative pass/fail test
that an individual would conduct to assess whether the mask is properly
fitted is a smell test. If you can smell an odorous substance through
the mask, it's not tight-fitting enough.
What's more, this test only needs to be done once, when selecting
the best-fitting brand, make, model and size of the respirator. Once
you know which model fits your face best, you don't need to do the fit
test again until or unless your facial structure changes due to dental
or cosmetic surgery, for example, or "an obvious change in body
weight." Health care workers, however, must do the fit test once a year
regardless, in order to maintain NIOSH compliance.
What Does the Research Say?
So, what's the real deal on the use of face masks? Do they only
protect health care workers from getting sick, and sick patients from
spreading it to others, or might they prevent healthy lay people from
being infected as well? A 2009 study10
in Emerging Infectious Diseases sought to answer this question in the
wake of the bird flu (H5N1) outbreak. According to the authors:11
"Many countries are stockpiling face masks … to reduce viral
transmission during an influenza pandemic. We conducted a prospective
cluster-randomized trial comparing surgical masks, non–fit-tested P2
masks, and no masks in prevention of influenza-like illness (ILI) in
households.
During the 2006 and 2007 winter seasons, 286 exposed adults from
143 households who had been exposed to a child with clinical
respiratory illness were recruited … Adherence to mask use was
associated with a significantly reduced risk of ILI-associated
infection.
We concluded that household use of masks is associated with low
adherence and is ineffective in controlling seasonal ILI. If adherence
were greater, mask use might reduce transmission during a severe
influenza pandemic."
In other words, mask use was ineffective due to low adherence, not
because they don't prevent the transmission of illness. In fact, were
more people to wear masks, infection rates would probably be lower.
Face Masks 'Underappreciated' for Infectious Control
Then there's the article12
"Disrupting the Transmission of Influenza A: Face Masks and
Ultraviolet Light as Control Measures," published in Health Policy and
Ethics in 2007, which states:
"In the event of an influenza pandemic, where effective
vaccine and antiviral drugs may be lacking, disrupting environmental
transmission of the influenza virus will be the only viable strategy to
protect the public. We discuss two such modalities, respirators (face
masks) and ultraviolet (UV) light.
Largely overlooked, the potential utility of each is
underappreciated. The effectiveness of disposable face masks may be
increased by sealing the edges of the mask to the face. Reusable masks
should be stockpiled, because the supply of disposable masks will likely
prove inadequate …
Respirators (N–95 and N–100; both commercially available) are
masks designed to shield the wearer from inhalational hazards, as
opposed to surgical masks, which are designed to protect others from
contaminants generated by the wearer. In the discussion that follows,
use of the word mask refers only to the former …
Current respirator filters are typically made of polypropylene
wool felt, or fiberglass paper. Particles collide with and become
enmeshed within these nonwoven fibers. Another mechanism for the
filtering media may be the electrostatic charge that these fibers have,
which attract and hold oppositely charged particles. The influenza
virus has charges at its hemagglutinin spikes …
N95 respirators … have been reported to be protective in
preventing transmission of the severe acute respiratory syndrome (SARS)
virus … but use of these masks failed to prevent a cluster of cases in
one hospital.
If one assumes that influenza is transmitted by respiratory
droplets (… which immediately fall to the ground) rather than by
aerosols (… which remain suspended in air for long periods of time),
the supposition may be that keeping a safe distance may obviate the need
for a face mask.
It is stated that the range of such droplets is generally no
more than 3 ft. We are unable to locate the basic science behind that
assertion … Laschtschenko found that talking sprayed viable bacteria 6 m
(approximately 20ft).
Koeniger … found that even whispering sprayed bacteria … 7.4 m
(approximately 24 ft) and a mixture of coughing, speaking, and
sneezing carried bacteria 12.4 m (40 ft) … From these very old reports,
the distinction between respiratory droplets and aerosols may be more
apparent than real.
As a respiratory droplet falls to the ground, the aqueous
portion quickly evaporates, but the bacterial or viral portion remains.
Theoretically, a viral particle, if it remains viable, could be
carried by wind or reaerosolized by ground disturbances."
The paper does highlight several factors that can render respirator
masks unreliable and ineffective. There's the issue of fit and seal
against the face, the fact that they cannot be repeatedly reused, the
risk of contact contamination when touching or removing the mask, and
the fact that your eyes are also a portal for viral infection.
Still, N95 and N100 respirators "offer the potential of mitigating a
potentially uncontrollable pandemic," the authors note, adding "It is
our hope that this brief review … draws the attention of policymakers
to allow for wider implementation of their use as public health
measures."
Mask Use May Not Be Effective in Isolation
All of that said, studies13,14
looking at disease transmission rates among people who use either face
masks or N95 respirators have shown conflicting results. Some conclude
they lower the risk of infection while others find they're no more
effective than handwashing. The following excerpt from a systematic
review published in 2012 is a case in point:15
"There are limited data on the use of masks and respirators to
reduce transmission of influenza … Inclusion criteria included
randomized controlled trials and quasi‐experimental and observational
studies of humans … with an outcome of laboratory‐confirmed or
clinically‐diagnosed influenza and other viral respiratory infections.
There were 17 eligible studies. Six of eight randomized
controlled trials found no significant differences between control and
intervention groups (masks with or without hand hygiene; N95/P2
respirators).
One household trial found that mask wearing coupled with hand
sanitizer use reduced secondary transmission of upper respiratory
infection/influenza‐like illness/laboratory‐confirmed influenza …
One hospital‐based trial found a lower rate of clinical
respiratory illness associated with non‐fit‐tested N95 respirator use
compared with medical masks.
Eight of nine retrospective observational studies found that
mask and/or respirator use was independently associated with a reduced
risk of severe acute respiratory syndrome (SARS) …
None of the studies established a conclusive relationship
between mask/respirator use and protection against influenza infection.
Some evidence suggests that mask use is best undertaken as part of a
package of personal protection especially hand hygiene. The
effectiveness of masks and respirators is likely linked to early,
consistent and correct usage."
A 2015 systematic review came to similar conclusions, stating:16
"The concepts of droplet and airborne transmission that are
entrenched in clinical practice have recently been shown to be more
complex than previously thought.
Several randomized clinical trials of facemasks have been
conducted in community and healthcare settings, using widely varying
interventions, including mixed interventions (such as masks and
handwashing), and diverse outcomes.
Of the nine trials of facemasks identified in community
settings, in all but one, facemasks were used for respiratory
protection of well people. They found that facemasks and facemasks plus
hand hygiene may prevent infection in community settings, subject to
early use and compliance."
Recommended Infection Prevention Strategies
At present, health authorities recommend using the following strategies to minimize the spread of infection:17
Frequently wash your hands with soap and water for at least 20 seconds
Avoid touching your eyes, nose and mouth
If you need to cough, cough into your flexed elbow or disposable tissue. Discard the tissue in a trash can and wash your hands
If feeling unwell, stay home and avoid public spaces
If you have symptoms of illness such as coughing or sneezing, be
sure to wear a surgical mask to contain the spread whenever you're
around others. As for whether or not you should wear a mask to prevent
contracting COVID-19 (or some other infectious disease), the answer is a
bit more elusive.
Based on the published evidence, however, it appears it can be at least moderately helpful provided you're:
Consistent in its use
Using an N95 or N100 respirator mask and putting it on correctly to ensure a proper seal
Not touching the mask while wearing it (if droplets have landed on
the mask, the viruses in the droplets are still infectious and can
transfer to your hands. So, if you touch the mask, you need to wash
your hands)
Removing it correctly (for the same reason as above)
Using it concomitant with frequent handwashing and other basic hygiene recommendations
Global Shortage of Face Masks
As reported by The Washington Post,18
face masks of all kinds are now in such short supply, even hospitals
are having a hard time getting enough. Mike Bowen, executive vice
president of Prestige Ameritech, the largest U.S.-based manufacturer of
surgical masks, claims he's been warning governments about the coming
of this day.
"This is the precise scenario he began warning about almost 15
years ago, when he pleaded with federal agencies and lawmakers to boost
U.S. production of medical masks," The Washington Post writes.19
"He had predicted an eventual health scare and not enough
manufacturers. He was right … 'What I've been saying since 2007 is,
'guys, I'm warning you, here's what is going to happen, let's prepare,'
Bowen said … 'Because if you call me after it starts, I can't help
everybody.'
The coronavirus outbreak has … exposed major vulnerabilities in
the medical supply chain. Many U.S. companies, especially hospitals and
pharmaceutical firms, rely on Chinese manufacturers for products … like
masks and gloves. Now, much appears upended.
There is no global, centralized plan for fast-tracking
production of what's known as personal protective equipment … 'Prestige
Ameritech is presently the lone voice warning of the insecure U.S.
mask supply,' Bowen wrote to President Barack Obama in June 2010 …
'The U.S. protective mask supply could — and mostly likely would
— be disrupted, confiscated or diverted in the event of a pandemic,'
Bowen wrote to President Trump three years ago … 'A lack of
planning on their part is not an emergency on my part,' Bowen said.
'They had their chance. I told them over and over.'"
Still Many Unknowns Surrounding COVID-19
There's still an awful lot we don't know about COVID-19, its origin,
infection mechanisms, incubation and transmission rates, and its
treatment. At present, the incubation period appears to be somewhere
between two and 14 days, which isn't exactly a precise measurement.20
Complicating matters is the finding that you can spread the virus
during that incubation period, and may remain contagious for an
undetermined time even after you've recovered. January 30, 2020, German
doctors reported21 a case of transmission from an asymptomatic carrier, saying:
"… it is notable that the infection appears to have been
transmitted during the incubation period of the index patient, in whom
the illness was brief and nonspecific. The fact that asymptomatic
persons are potential sources of 2019-nCoV infection may warrant a
reassessment of transmission dynamics of the current outbreak.
In this context, the detection of 2019-nCoV and a high sputum
viral load in a convalescent patient (Patient 1) arouse concern about
prolonged shedding of 2019-nCoV after recovery."
As for how it spreads, the virus can pass from one person to another
through respiratory droplets emitted when talking, coughing or
sneezing. Aside from breathing the virus in, you may be infected by
touching a contaminated surface, or when shaking hands or sharing a
drink or utensils with an infected person22 — whether asymptomatic or symptomatic, and possibly for some days after they've recovered.
Now, if COVID-19 can spread during the incubation period and for
some time after recovery, wearing a face mask as a precautionary
strategy may be rather sensible. After all, surgical masks are meant to
limit the spread of the virus.
If you don't know whether you've been exposed, you won't know if
you're contagious. So, limiting the wearing of face masks to people who
are already symptomatic means people will be walking around spreading
the disease for up to two weeks. If they're wearing a mask, they limit
the spread of the contagion.
While not a short-term solution for the current shortage of
protective masks, perhaps it would be wise to increase global
production in preparation for these kinds of outbreaks, just like Bowen
has suggested for the past 15 years.
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