As the coronavirus pandemic rages on, people are looking for ways they can protect themselves and others from infection.
While cloth facial coverings are now ubiquitous in many parts of the country, clear plastic face shields have been slower to catch on with the public. (The gear is most commonly worn in health care settings, on top of a surgical mask or N-95 respirator). But interest seems to be growing: Google Trends data shows a large spike in searches for the term “face shields” over the last two months. And the new curiosity about face shields has raised questions about how well they protect against COVID-19.
First, know that the novel coronavirus is thought to be spread mainly through the respiratory droplets produced when an infected individual coughs, sneezes or speaks. Transmission primarily occurs during close person-to-person contact and, less commonly, via contaminated surfaces. Now some experts say it may also be transmitted via aerosols — or microscopic particles that can linger in the air far longer than larger, heavier droplets.
Currently, the Centers for Disease Control and Prevention is not recommending face shields for everyday activities or as a substitute for cloth face coverings.
However, some experts — such as Eli Perencevich, a professor of internal medicine and epidemiology at the University of Iowa Carver College of Medicine — believe that face shields could potentially be more effective than cloth face masks in the community setting. In an opinion piece Perencevich co-authored for the Journal of the American Medical Association in April, he and his colleagues cited a 2014 study from the National Institute for Occupational Safety and Health (NIOSH) that looked at how well face shields protected a simulated health care worker against influenza (a different respiratory virus). They found that the face shield reduced immediate viral exposure to the flu by 92% when worn within 6 feet of a cough.
That said, there are no studies that examine how well face shields protect other individuals from the wearer’s own respiratory droplets, should they be infected — which is the main reason the CDC recommends facial coverings be worn in public in the first place.
“We don’t have the research to say that [face shields] will offer protection for those around you, should you be sick,” Saskia Popescu, an infection prevention epidemiologist at George Mason University, told Self magazine.
Face shields may offer some benefits...
Though studies on the efficacy of face shields are limited, they may have some advantages over cloth face masks.
They protect your eyes, in addition to the nose and mouth.
A face mask covers the lower part of the face but leaves the eyes exposed.
With a face shield, “you get the additional coverage of your eyes, another mucous membrane that may act as a portal of entry for the virus,” Erin Sorrell, an assistant research professor in Georgetown University’s department of microbiology and immunology, told HuffPost. “However, research needs to be done to quantify the risk for ocular route of exposure.”
A proper face shield should extend down below the chin, around the sides of the head to the ears and have no gap between the headpiece and the forehead.
They allow you to see people’s mouths and other facial expressions.
We all depend on non-verbal communication — like facial expressions — when interacting with others. But the ability to read lips is particularly important for those who are hard of hearing.
Krutika Kuppalli, an infectious diseases physician and vice chair of the IDSA Global Health Committee, had an ear injury a couple of years ago that affected her hearing. Working in environments where masks are necessary can be challenging at times, she said.
“When people are wearing masks, you lose that ability to verbally read people’s mouths and the facial cues when they’re talking,” she said. ”When you lose that, it can make it very difficult to communicate.”
They’re easier to clean and safely reuse.
Disposable face coverings, like surgical masks, should be discarded after use. Cloth facial coverings can be reworn but need to be washed (ideally in a washing machine) and dried after each use, which takes time.
“With face shields, you can reuse them indefinitely and they’re easily cleaned with soap and water or other household disinfectants,” Kuppalli said.
They may be more comfortable to wear, making you less likely to touch your face.
“People who wear these homemade cloth masks are invariably touching their face constantly to adjust it, and we know that touching your face is one routine mechanism for infecting you,” Amesh Adalja, a senior scholar at the Johns Hopkins University Center for Health Security, told NBC News. “When you’re wearing a face shield, you’re less likely to touch your face.”
Face shields may also be a more comfortable option for people who wear glasses or who have trouble breathing while wearing a mask, Sorrell added. Plus, pulling your mask up and down without washing your hands first can lead to contamination.
“A properly worn face shield is much more effective than a face mask that is removed when speaking or worn under your nose or around your neck,” Sorrell said. “If you aren’t going to wear and use a face mask properly, you are not going to be protected or protect others.”
...But they have other limitations and disadvantages, too.
Unlike masks, which “provide a closer seal to the wearer’s face,” Sorrell said, face shields are open on the sides and bottom of the face, which may allow particles to seep in or out.
“If you’re facing sideways or I’m behind you, maybe you’re sitting at a desk and I’m standing, there’s other scenarios you can imagine where droplets can come around a face shield,” William Lindsley, a NIOSH bioengineer who conducted the influenza study, told The New York Times.
That’s why some public health officials recommend draping a piece of cloth along the bottom of the face shield to create a better barrier, Sorrell noted.
While a face shield may do a good job at blocking larger viral particles, Lindsley said that cloth facial coverings or medical masks offer more protection from tinier ones.
“A face shield is good against the really big stuff [particles] that you can kind of see,” he told NBC News. “But as the stuff gets smaller and smaller, it’s just easy for that to go around the face shield and be inhaled.”
Until we have more research, a face mask is your best bet.
“We don’t have enough large-scale data to show the true effectiveness of face shields against COVID-19 compared to face masks,” Sorrell said.
For now, if you’re going to wear a face shield, you should do so in addition to — not in lieu of — a face mask.
However, “the average person who wears a face mask correctly and maintains social distancing does not need the added layer of a face shield,” Sorrell noted.
And, of course, any protective gear should be used in conjunction with other safety measures, such as physical distancing and frequent hand washing, not in place of them.
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Experts are still learning about the novel coronavirus. The information in this story is what was known or available as of press time, but it’s possible guidance around COVID-19 could change as scientists discover more about the virus. Please check the Centers for Disease Control and Prevention for the most updated recommendations.