En español | Face shields are a common sight in doctors’ offices and hospitals. And as the pandemic drags on, they are becoming more prevalent among the public, too. But how do they work? And just how effective are they when it comes to protecting against the new coronavirus? AARP asked the experts for their take on the advantages and disadvantages of face shields.
Pro: Face shields protect the entire face
One of the benefits of face shields is that they protect the entire face, including the eyes, which along with the nose and mouth can be a gateway for the coronavirus and other germs to enter the body. The plastic panel that hangs from the top of the forehead and extends below the chin prevents large respiratory droplets that are thought to carry the virus from reaching these areas of potential infection.
Face shields also reduce the likelihood that you'll introduce virus-packed particles on your own — think of them as a dog cone for humans, says Gonzalo Bearman, M.D., a hospital epidemiologist and chair of the Division of Infectious Diseases at Virginia Commonwealth University (VCU) Health. They keep you from touching “your hands to your eyes and nose and mouth. If you're wearing one, it's pretty hard to do that,” he says.
Currently, the Centers for Disease Control and Prevention (CDC) does not recommend face shields for the general public, especially as a substitute for face masks. (Experts in favor of them say if you're going to wear one, it should be in addition to a cloth face mask that covers your nose and mouth.) The agency, however, does advise health care workers to wear them (or some other form of eye protection) along with face masks, especially in areas that are experiencing moderate to substantial spread of COVID-19. And Eli Perencevich, M.D., professor of internal medicine and epidemiology at the University of Iowa Carver College of Medicine, says concerned individuals, and notably those at high risk for severe illness from COVID-19, should consider doing the same.
"Health care workers wear masks and face shields because it's dangerous in health care, but when you have a pandemic, it's dangerous in the community,” says Perencevich, who coauthored a letter in the Journal of the American Medical Association (JAMA) championing more widespread use of face shields. “The whole point of face shields is to get people to think about personal protective equipment in the community, and masks alone are not personal protective equipment.”
A recent JAMA report found that when community health workers added face shields to other protective equipment (face masks and gloves), COVID-19 infection rates among the workers dropped to zero. Similar findings have been published in The Lancet: Researchers looked at studies evaluating the effectiveness of nonpharmacologic interventions and found that eye protection was associated with a lower risk of virus infection. “Eye protection is typically underconsidered and can be effective in community settings,” the report's authors write.
"It's double protection,” Perencevich says about layering a face shield over a cloth face covering. “The face shield will protect the mask from being contaminated and then block additional droplets from your whole face, including your eyes.”
Con: Face shields are not as effective at protecting others
The chief reason the CDC recommends face masks is because they serve as a form of “source control,” meaning they help to prevent people who have COVID-19 from transmitting the virus to others by blocking respiratory particles from traveling into the air and on to other people. When worn correctly and universally, they can reduce the spread of disease in a community.
Face shields also have the ability to block respiratory droplets produced by the wearer from spreading to others, but it's unclear how well, the CDC says. A new study published in the journal Physics of Fluids highlights a downside of face shields when it comes to controlling droplet spread. Using test dummies and laser sheets, researchers found that when a person wearing a face shield coughs or sneezes, a plume of aerosol-sized droplet particles escapes from the gaps in the bottom and on the sides of the shield.
"Over time, these droplets can disperse over a wide area in both lateral and longitudinal directions, albeit with decreasing droplet concentration,” study coauthor Manhar Dhanak, a professor at the Florida Atlantic University College of Engineering and Computer Science, said in a statement.
"Masks are really about protecting others — that data is really strong,” Perencevich says. “Face shields are about protecting the wearer. If you have to be in the community, any kind of cotton mask or medical mask and a face shield is really ideal protection.”
Pro: It's hard to wear a shield incorrectly
Unlike masks — which people tend to let slip under their nose, or worse, off their face completely — “it's hard to wear a face shield incorrectly,” Perencevich says.
Just make sure it's positioned properly: The forehead band should sit approximately 1/2 inch to 1 inch above the eyebrows, according to a University of Iowa Health Care explainer, and the bottom of the shield should sit below chin level.
Con: But face shields can be uncomfortable
Those who find masks uncomfortable and are in search of an alternative may be disappointed to learn that face shields have a few drawbacks, as well. For starters, they can be bulky to wear, Bearman points out — especially the shields that wrap around the sides of your face to maximize protection. They can also “get steamy and fog up.” As well, people who wear face shields on top of their masks may find they need to speak louder and more clearly when communicating with others.
Bearman points out that when it comes to public health interventions, “you have to think of whether it's pragmatic and will play out in the day to day.” And he isn't confident that the public is ready to take on face shields in addition to masks. Adding that extra layer “will likely be uncomfortable for people,” he says.
Pro: Face shields are easy to find
Similar to cloth face masks, which are everywhere these days — from high-end retail shops to convenience stores — face shields are also easy to find. Your best bet is the internet, where a pack of two reusable shields will cost between $10 and $20. More elaborate models (a face shield with a fashionable hood, for example), will run you about $50.
Con: Be wary of low-quality models
Just make sure that if you purchase a face shield, you get one that provides sufficient coverage. (Some models shield only the mouth and nose, for example.) Look for one that is “sealed at the top” onto a visor and wraps around the sides of your face to your ears, Perencevich says. The bottom of the shield should extend below the chin.
And just like face masks, shields need a little routine care to ensure effectiveness. Reusable shields should be cleaned and disinfected after each use, the CDC says. Face shield wearers should also wash their hands before and after removing the shield and avoid touching their eyes, nose and mouth when removing it.
Equipment alone will not prevent COVID-19
Even with a face shield and a face mask, Perencevich says it's important to follow other guidelines to protect yourself from a coronavirus infection: Avoid close contact with individuals outside your household and steer clear of crowded settings — especially indoor spaces with poor ventilation. Wash your hands often, and clean and disinfect high-touch surfaces.
"No amount of personal protective equipment is 100 percent safe,” Perencevich says. “We still have to do all the other things.”