As the number of COVID-19 cases continue to rise in the US, so too do the reported symptoms that are caused by the coronavirus—most recently, according to experts, conjunctivitis, otherwise known as pink eye, or an irritation of the eye that causes redness, swelling, and sometimes discharge.
In an alert updated on Tuesday, the American Academy of Ophthalmology (AAO) reported that coronavirus “can cause a mild follicular conjunctivitis otherwise indistinguishable from other viral causes.” The organization went on to explain that the conjunctivitis—which affects an estimated 1-3% of those with COVID-19—is possibly transmitted by “aerosol contact with the conjunctiva,” or the mucous membrane that covers the eye.
Coronaviruses are a group of related viruses that cause diseases in mammals and birds. In humans, coronaviruses cause respiratory tract infections that can be mild, such as some cases of the common cold (among other possible causes, predominantly rhinoviruses), and others that can be lethal, such as SARS, MERS, and COVID-19. Symptoms in other species vary: in chickens, they cause an upper respiratory tract disease, while in cows and pigs they cause diarrhea. There are yet to be vaccines or antiviral drugs to prevent or treat human coronavirus infections.
Coronaviruses constitute the subfamily Orthocoronavirinae, in the family Coronaviridae, order Nidovirales, and realm Riboviria. They are enveloped viruses with a positive-sense single-stranded RNA genome and a nucleocapsid of helical symmetry. The genome size of coronaviruses ranges from approximately 27 to 34 kilobases, the largest among known RNA viruses. The name coronavirus is derived from the Latin corona, meaning “crown” or “halo”, which refers to the characteristic appearance reminiscent of a crown or a solar corona around the virions (virus particles) when viewed under two-dimensional transmission electron microscopy, due to the surface being covered in club-shaped protein spikes.
Pink Eye May Be a Rare, Early Sign of Coronavirus
It’s not uncommon for a viral illnesses to show up in the eyes. “Many viral illnesses can affect the eye, typically causing a follicular type of conjunctivitis,” Vicente Diaz, MD, a Yale Medicine ophthalmologist, tells Health. “We are learning that COVID-19 can affect the conjunctiva in a low percentage of people,” he says, adding that, in those who have these ocular symptoms, the eye’s secretions may also be able to transmit the virus.
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Pink Eye May Be a Rare, Early Sign of Coronavirus
The AAO’s alert included two published reports, which suggest the link between COVID-19 and conjunctivitis. The first, a small February 2020 study in the Journal of Medical Virology, which found that one patient among 30 who had been hospitalized in China for COVID-19 had conjunctivitis, and had coronavirus (SARS-CoV-2) in their ocular secretions. The other larger study, published in February 2020 in the New England Journal of Medicine, claimed that, of 1,099 patients across 30 different Chinese hospitals, nine had “conjunctival congestion.”
The AAO also referenced reporting from CNN, which highlighted a registered nurse from a Washington-based nursing home, who shared that visibly red eyes were common among elderly patients who went on to become sick with COVID-19.
While the AAO says that conjunctivitis or pink eye may be an uncommon but still present symptom of COVID-19, it’s also important to remember that many other things can cause conjunctivitis as well, like other viruses, bacteria, and even allergies—the last of which would be a much more likely cause of pink eye right now, with spring allergy season upon us, says Dr. Diaz.
If you do have symptoms of conjunctivitis—coupled with respiratory symptoms and a fever—call your physician first before you go in because you might be COVID-19 positive, urges Kevin Lee, MD, an eye physician and surgeon from the Golden Gate Eye Associates within the Pacific Vision Eye Institute. The AAO also warned eye doctors and emergency physicians that, the presence of conjunctivitis “increases the likelihood ophthalmologists may be the first providers to evaluate patients possible infected with COVID-19.”
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For the rest of us, this information should serve as a reminder that the virus can spread via eye droplets. “Crying and other ocular secretions can also transmit the virus, if a person is COVID-19 positive,” says Dr. Lee. Obviously, this isn’t the time to share makeup or other cosmetics with your friends or family. “To avoid possible transmission, do not share cosmetics or eye drops,” Dr. Lee adds.
And again, diligent hand washing hygiene is key. “People don’t realize how often they touch their face, so please be cognizant,” says Dr. Lee. “Avoid rubbing your eyes or touching your face especially after contact with public surfaces.”
The information in this story is accurate as of press time. However, as the situation surrounding COVID-19 continues to evolve, it’s possible that some data have changed since publication. While Health is trying to keep our stories as up-to-date as possible, we also encourage readers to stay informed on news and recommendations for their own communities by using the CDC, WHO, and their local public health department as resources.
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