Some Experts Say Face Shields Better Than Masks for Coronavirus Protection
By now we know we should be wearing face masks to protect others from
potentially deadly infection when we leave the house. But face masks can be
hot, and they can irritate the skin, fog glasses, make it difficult for some to
breathe and create a world without smiles. It also can be difficult for people
who have hearing loss to communicate when mouths are covered, muffling voices
and hiding facial expressions.
Are clear plastic face shields, most frequently used in health care
settings, a better option?
The Centers for Disease Control and Prevention continues to recommend wearing " cloth face coverings in public settings where other
social distancing measures are difficult to maintain.” But some health experts
say shields appear to be very effective at preventing infection — maybe even
more effective than masks — for someone going about regular daily activities
and not in a high-risk health care setting.
Amesh Adalja, M.D., a pandemic preparedness expert at the Johns Hopkins
Center for Health Security, says, “There's a lot of at least biological
possibility to suspect that [shields] are definitely better than homemade face
masks, and maybe even better than other types of masks as well, because they
not only prevent you from spreading it … [and] because it also covers your
eyes, it provides more protection to the mucus membranes of your face where you
might be getting infected.”
James Cherry, M.D., a distinguished research professor and infectious
disease expert at the David Geffen School of Medicine at UCLA, says that while
experts aren't yet sure about how vulnerable our eyes are to infection from this coronavirus, “With many viruses, the eyes are
important.” He points to measles and adenoviruses as examples of viruses that
are known to infect people through their eyes.
Another benefit, says Adalja: With a
mask, you may find yourself constantly adjusting it and therefore touching your
face and possibly transferring the virus from your hands, but wearing a shield
“doesn't really put you in a position where you're touching your face so much,
because it's not as cumbersome to wear."
And finally, Adalja adds, “If you
walk down the sidewalk, you can find lots of masks that are just discarded
there, which are an infection control risk for other people. Whereas a face
shield is something that people can just clean themselves and reuse."
Eli Perencevich, M.D., a professor of
internal medicine and epidemiology at the University of Iowa Carver College of
Medicine, and two of his colleagues pointed to such benefits of shields for
infection prevention, and noted that “face shields appear to significantly
reduce the amount of inhalation exposure to influenza virus, another
droplet-spread respiratory virus. In a simulation study, face shields were
shown to reduce immediate viral exposure by 96 percent when worn by a simulated
health care worker within 18 inches of a cough.” In an April 19 tweet
Perencevich wrote, “Biggest benefit of face shields would be inside crowded
office situations where air exchanges aren't ideal."
Another benefit? With warmer
weather, many may also find a face shield attached to a headband or cap cooler
to wear than a cloth mask.
Some members of the public are
taking such arguments to heart — choosing shields especially for their ability
to keep the entire face visible.
Lauren Lek, head of school at
Academy of Our Lady of Peace, in San Diego, plans to have her 750 returning
faculty and students wear face shields at school rather than masks this August.
“Safety and health for our community is a priority for us in reopening,” she
says. “As soon as we saw from the CDC [Centers for Disease Control and
Prevention] and our local public health office that face shields would be an
acceptable alternative to face masks, we knew this was a direction we wanted to
move in.”
Noting that face-to-face interaction
is key to the education her school provides, Lek adds that face shields are
better than masks for students with learning differences, including autism spectrum
disorders (ASDs), because they allow for full visibility of facial expressions
that can help them read and understand social cues.
The school has purchased more than
10 different types of face shields to test before classes restart, Lek says,
with each posing challenges in terms of clarity, fogging, ease of cleaning and
reuse. They also shouldn't cause headaches when worn 10 hours a day. “With each
product we try, we are getting closer to the best option for the start of
school in August.”
Double
protection?
Some people are choosing both
infection-prevention methods. Hope Taitz, an investment manager in New York
City who travels frequently for business, began wearing a face mask and face
shield together when she saw the pandemic starting to unfold while logging
100,000 miles of travel in January and February. She said one of the best
things she saw traveling in Asia were deep bubble umbrellas that can cover you
from head to midsection.
You're likely to find only health
care workers wearing both a shield and a mask simultaneously, however. “I don't
wear the shield alone,” says Anne Mary Orr, a dentist in private practice in
Broken Bow, Oklahoma. “At work, the whole point of the shield is to keep
particulate matter off the mask. The N95 mask I wear under it helps filter
breathing the virus. Our greatest risk is to inhale an aerosol at work, more so
than focusing on the droplets.”
Kristi Carnahan, a registered nurse
in the Emergency Department at Stanford Hospital in Palo Alto, California, says
she also wears a mask beneath her plastic face shield to provide more
“protection against anything in the air getting into your mouth or nose as you
breathe."
That reasoning may make sense in a
health care setting, says Adalja, but “I don't think you get much added benefit
to wearing a mask if you've already got a face shield on, for the average
person.” The odds of the viral particles floating upwards under your shield are
a long shot for most of us, he adds: “Someone would have to stand underneath
you and sneeze up into you. It would be an odd circumstance that would cause
that.”
Keeping
the mouth visible
Carnahan acknowledges that masks are
difficult for people like herself who have hearing difficulties. She says she
finds herself asking colleagues to repeat themselves frequently when she cannot
see their mouths. “It is a reality for many who rely on lip reading or ASL
[American Sign Language] that masks make communicating much harder,” she notes,
“especially because facial expressions are an integral part of American Sign
Language."
While it doesn't explicitly
recommend the use of face shields, The American Speech-Language-Hearing
Association (ASHA) recently sent a letter to CDC Director Robert Redfield
asking the agency to emphasize the need for clear face masks and other
communication aids in health care settings to help people with hearing and
other communication disorders. “If a patient doesn't hear/understand properly,
there could be serious consequences like adverse medical events,” says ASHA
spokesperson Francine Pierson. Brigham and Women's Hospital in Boston, for one,
has begun using special masks with transparent cutouts making the mouth visible
for health care workers speaking to patients with hearing loss.
Whatever you decide to wear to
prevent infection when you're out and about, keep in mind that staying safe
from COVID-19 means putting in place multiple safeguards, including thorough
handwashing.
The most important safety measure,
though, is social distancing, Cherry says. “The virus is in these droplets, and
they don't go very far — they fall to the ground. So that's why [staying] 6
feet away from others is the most important thing that we can all do."
Where
to buy shields
Shields come attached to hats or
attach to glasses or headbands. You can buy them online, often for less than
$20, at sites such as Gearbest, Pro-Tex and Amazon. Some manufacturers, like
RealShield by Racing Optics Inc., are making face shields with UV coatings.
"For optimal protection,”
Perencevich and his colleagues assert in their JAMA article, “the shield should
extend below the chin anteriorly, to the ears laterally, and there should be no
exposed gap between the forehead and the shield's headpiece.”