Medical Examiner

Should You Buy a Face Shield?

What we know—and what we don’t—about stopping the coronavirus by attaching a plastic sheet to your head.

people wearing sheets of plastic over their faces
Photo illustration by Slate. Photos by Adem Altan/AFP via Getty Images, Nicolas Maeterlinck/BELGA/AFP via Getty Images, Raul Valcarcel/iStock, Ezra Acayan/Getty Images, and Ozan Kose/AFP via Getty Images.

Here’s a charming face shield that will run you $16.50 on Etsy. Designed for teachers, it has an adjustable band, a sheet of clear plastic to cover your face, and a customizable “black board” on the forehead, where the vendor will print your name in a calligraphic font. Here’s another face shield from the same seller that features a unicorn horn and ears across the forehead, with the wearer’s name below the chin in pink. Here are some face shields for kids with bears and sharks and mermaids. Here are some plain clear face shields with 11 color options for the headband.

We’re well past the point of the pandemic where face masks can be fashionable—and now face shields are, too. While the headgear has been a regular sight in medical settings since the spring, they’re beginning to appear more in public spaces as states reopen (even as the virus shows no sign of slowing down). So, should you get one?

Some doctors and teachers have suggested that plastic face shields could be a good substitute for masks—after all, they appear to offer protection while not hiding facial expressions. You probably shouldn’t do that. Instead, health experts are urging people to consider face shields as an additional piece of protection on top of a mask (a point that some sellers are careful to make through images and disclaimers). “Theoretically, you should protect all the mucosal surfaces,” Anthony Fauci told ABC recently. “So if you have goggles or an eye shield, you should use it.”

Here’s what we know, and what we don’t, about how face shields can protect us from contracting the coronavirus. Right now, the published research on them consists of one paper from 2014: “Efficacy of Face Shields Against Cough Aerosol Droplets From a Cough Simulator.” Researchers put a face shield on a head form encasing a breathing machine, and placed it a few feet from another head form spewing droplets of influenza. They measured how much influenza made it behind the face shield, into the mouth of the head form, and down the breathing machine. The face shield did a good job of blocking the cough at first, catching the big droplets. But as the minutes went on, smaller droplets—aerosols—made their way behind the shield. “You put on a face shield and I squirt you in the face with a squirt gun—in that case, the face shield works great,” William Lindsley, a bioengineer at the Centers for Disease Control and Prevention and the first author of that paper, told me. “If I blow cigarette smoke in your face, the smoke lingers in the air. After five minutes, you’re still breathing in the smoke.” It’s also not clear how well face masks work as source control—that is, as a barrier to particles as they leave someone’s mouth, as masks are intended to do. (On source control, “we’re trying frantically to get some experiments going to see what we can find out,” Lindsley said.) Since shields do block some stuff from reaching the wearer, the 2014 paper concluded that in a health care setting a face shield could be a worthwhile addition to a mask.

In addition to offering a little extra protection from splashes of virus, and keeping a mask a little cleaner in particularly germy places, face shields offer some eye protection. Our eyes are connected to our noses via the nasolacrimal duct. “The importance of eye protection in the prevention of COVID-19 and other coronaviruses is underappreciated,” an article in the journal Infection Control & Hospital Epidemiology argues. There’s evidence that eye infections are possible: Two monkeys were successfully infected with the coronavirus via their eyes, according to a paper that hasn’t yet been peer-reviewed. Another paper, also not yet peer-reviewed, describes a study of 72 patients with COVID-19 in which researchers found a virus in the eyes of one patient. “We suspect the incidence of SARS-COV-2 infection through the ocular surface is extremely low,” the paper says, though they also note their sampling method may have failed to catch some instances of eye-virus, and since their work supports that it can happen, they urge health care workers to use eye protection. After all, even if infection via the eyes is on the rarer side, they’re interacting with many people who are or could be shedding the virus—people who, in order to receive tests and care, might not be wearing masks constantly while in contact with health care workers.

It’s the leap from health care professionals to everyday people needing this extra step of protection that makes the custom masks with apple and flower illustrations so striking to me—we’re so deep into this now that cutesy PPE has become reasonable and smart. “If you’re an essential worker, you absolutely have to wear a mask and face shield,” Eli Perencevich, an infectious disease doctor at the University of Iowa, and an author of the Infection Control article, told me. “Especially if you’re an older teacher, I think I wouldn’t feel safe with one or the other,” said Perencevich. He’s also in favor of people in low-risk situations being able to choose between a face shield, particularly one that bends around the face like this, or a mask (a position that goes against current CDC recommendations). He cited Lindsley’s 2014 paper as evidence that the shields do block the immediate spew of particles, which, epidemiologically, he considered enough. Pushing back, leading aerosol expert Linsey Marr emphasized that face shields “do almost nothing” against those really tiny particles that people can inhale, whereas masks offer far more protection. Still, she sympathized with the idea that one might want to communicate with other people and not have cloth over one’s mouth. “I’m going to have my group look into a face shield with a hood or a towel on it,” she told me. (What does that look like? It looks like this.)

One of the big reasons extra protection—whether from a mask and a shield, or possibly some kind of beekeeper-eqsue contraption—can be useful isn’t eye protection. It’s additional protection, on your whole face, from other people. That includes people who outright refuse to wear masks, and also children who have trouble keeping them on throughout the day. Having not just some eye protection, but extra protection overall, stands to cut down on the viral load wearers might receive. Of course, Perncevich offers the caveat that schools in areas with high case counts shouldn’t be opening at all; the PPE is meant to be a backstop, not a permission slip. But if you’re obligated to go to work under risky circumstances, protecting yourself as much as possible is wise. “With a face shield,” says Perencevich, “you’re less dependent on other people.”

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