Each week we answer pressing coronavirus questions. We'd like to hear what you're curious about. Email us atgoatsandsoda@npr.orgwith the subject line: "Weekly Coronavirus Questions."
How big a risk is it to catch the virus through your eyes? Should people be wearing eye protection?
Virologist and epidemiologist Dr. Joseph Fair recently became ill, and he believes he got COVID-19 through his eyes. Fair told NBC's Today from his hospital bed last week that he had been on a crowded flight two weeks earlier, and though he wore a mask and gloves and wiped down his seat, he didn't have any protection over his eyes. "You can still get this virus through your eyes, and epidemiologically, it's the best guess I have of probably how I got it," Fair said. He said his symptoms started three or four days later, though his four tests for the virus were negative.
The notion that you can get the virus through your eyes isn't new, but it has been little discussed compared with the risk of infection through the nose and mouth.
The CDC says that while the nose and mouth are the main avenues by which someone catches the coronavirus, "it may be possible that a person can get COVID-19 by touching a surface or object that has the virus on it and then touching their own mouth, nose, or possibly their eyes."
"Based upon what we know, I would say that the possibility of acquiring it on the surface of your eye is possible. It's certainly plausible," says , a spokesperson for the American Academy of Ophthalmology and professor of ophthalmology at MetroHealth Medical Center in Cleveland.
"Any sort of open mucosa [mucous membrane] is a chance for a droplet to land there and get into your body," says Dr. Abraar Karan, a physician at Harvard Medical School. But while it's known that the virus can be transmitted through the eyes, "it's hard to quantify exactly what the risk is in terms [of] through the eye specifically."
For most cases, it's impossible to determine with certainty the initial avenue of someone's infection – that is, whether a person was infected via their mouth, nose or eyes. And the evidence so far suggests that eyes are not a primary mode of transmission.
If a lot of people were being infected through their eyes, there would be more COVID-19 patients with conjunctivitis – inflammation of the eyes, also known as pink eye.
If the virus invades and infiltrates your conjunctiva – the clear tissue covering the white part of your eye and the inside of your eyelids – likely "there's going to be inflammation or redness in your eyes," Steinemann says. Of course there are many other causes for conjunctivitis, though, so getting pink eye doesn't necessarily mean you have COVID-19.
So far, studies have found that among hospitalized COVID-19 patients, only a small percentage of those who had the fluid in their eyes swabbed for the virus did in fact test positive for the virus in their eyes.
It should be noted, though, that eye swabbing is not standard practice for COVID-19 patients – in part because most people don't have much eye fluid, so swabbing it is uncomfortable.
And there's another reason why eyes are not a likely way to be infected with the coronavirus: The pathway from your eyes into your respiratory system is less direct than via your nose and mouth.
If an infectious person coughs or sneezes in your face, and you breathe in through your mouth or nose, not only are you going to receive a sizable viral dose, "you're going to get a fairly direct hit into your airways," Steinemann says.
But to infect you via your eyes, the virus would have to penetrate your eyes' mucous membrane, be washed by tears behind your cheeks into your nasal cavity, and then flow from the nose into your throat. "It's a more circuitous route," says Steinemann.
Our eyes have a number of defense mechanisms that help protect against infection, like eyelids that blink to cover the eye and tears that contain immunoglobulins that fight invaders.
"You blink really easily any time even a puff of air goes near your eye," says Dr. Emily Landon, hospital epidemiologist and infectious diseases specialist at University of Chicago Medicine. "So if somebody coughs or sneezes near you, you're really likely to close off your eyes. That's good. Whereas your mouth and nose don't do that."
What precautions should you take to protect your eyes?
The basic precautions against the coronavirus still hold when it comes to your eyes, says Steinemann: Wash your hands, practice social distancing – and "don't touch your face" also means don't rub your eyes.
With some airlines now asking flight attendants to wear safety goggles – Qatar Airlines is the latest to announce this plan — the general public might wonder: Should others do the same?
Karan says that in health care settings, eye coverings are immensely important. "We definitely don't go into [coronavirus patients'] rooms without eye coverings." He says other jobs that require people to work face-to-face, like a barber, might also choose to wear a full-face clear plastic shield.
Steinemann also says whether you need eye protection depends on your job. If you work in an office where you don't have to be in close proximity to people to others, you should be fine without eye protection.
On the other hand, he says, "if you are in close proximity to somebody screaming at you or talking to you or coughing in your face, or if you work in a hospital, suctioning people who are in an intensive care unit — those types of situations are extremely high risk, not only to your nose and your mouth, but also to your eyes. In a high-risk situation, I would definitely recommend the use of a full-face shield and goggles."
You don't need to be wearing a face shield on your walk around the neighborhood or your visit to the grocery store, he notes. For those situations, he recommends wearing a mask and practicing good hygiene and social distancing.
And what about the case of the virologist on the packed airplane?
Steinemann says if he was on a crowded airplane and unable to keep distance from other passengers, "Yeah, I think I might wear a face shield and a goggle in that setting."
Landon says that she has face shields at her home but has not yet found an activity where it felt necessary for her family to wear them. "But I am going to ask my mom to wear one when she takes a plane home from Florida – if I let her take the plane home from Florida."
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