A new COVID variant called Arcturus is linked to pink eye. Here's what you need to know.

About 1 in 10 cases of COVID-19 nationwide is caused by an emerging coronavirus strain, XBB.1.16.

The World Health Organization has elevated this strain of omicron to one of two "circulating variants of interest." The variant, which has been called Arcturus, is responsible for a growing share of coronavirus cases in the United States.

As of April 22, it caused 9.6% of COVID-19 infections nationwide, according to the Centers for Disease Control and Prevention.

Arcturus was first reported in January and has spread rapidly in other nations such as India and Indonesia.

Here's what you need to know.

How is Arcturus different from other coronavirus strains?

Infectious disease doctors say the strain's mutation in the spike protein makes it highly transmissible but doesn't cause more severe cases. Existing vaccines and coronavirus treatments that work on omicron appear to work well against XBB.1.16, said Dr. William Schaffner, an infectious disease specialist at Vanderbilt University Medical Center in Nashville, Tennessee.

But Arcturus differs from earlier strains in at least two ways.

"It tends to produce more fever than some of the other strains we've seen," Schaffner said. "But the most distinctive feature is that it seems to have a tendency to produce conjunctivitis, particularly in children."

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What is pink eye, aka conjunctivitis?

Conjunctivitis, known as pink eye, is an eye condition that can be caused by a virus, bacteria or allergies. Eyes turn red and swell and can produce a sticky discharge. It causes inflammation on the outer surface of the eyeball and eyelids.

The most common forms of pink eye spread easily from person to person.

How rare is COVID pink eye?

About 1% to 3% of patients with COVID-19 have had pink eye as a symptom, the American Academy of Ophthalmology said, citing studies based on earlier strains.

While there's no recent data about Arcturus and conjunctivitis, eye doctors and infectious disease specialists say there appears to be cases involving children though none could cite data showing how common these infections might be.

"Reports indicate that this is very much like other forms of viral conjunctivitis," Schaffner said. "It'll make you miserable for about a week with swollen eyelids, tearing and itching, but then you recover without any long term effects."

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Is it pink eye or allergies?

Red, itchy eyes also can be a sign of seasonal allergies. Allergies are common during the spring as pollen counts spike. If you are prone to allergies, you might consider reducing outdoor trips during spring months.

Dr. Ronald Benner, an optometrist and president of the American Optometric Association, recommended people see a doctor if they suspect an infection.

"It's hard to determine whether it originated from an allergy, or is it a bacterial infection or is it a viral infection?" said Benner.

Symptoms of COVID pink eye

Benner said some people who have developed COVID pink eye might not notice any other symptoms.

"With this new variant of COVID, sometimes conjunctivitis is the only sign," Benner said.

He added that in rare instances COVID pink eye cases can linger for two to three weeks.

Dr. Jeff Pettey, an associate professor at the University of Utah Department of Ophthalmology and Visual Sciences, said COVID pink eye symptoms are similar to other pink eye viral infections.

"Symptoms can range from very mild to severe with eye pain and cloudy vision from cornea involvement," Pettey said. "If someone has pink eye with other symptoms of COVID, they should test or seek medical care."

While all types of pink eye cause the eyes to become red, other symptoms differ depending on the type of infection, Benner said. A bacterial infection tends to have a lot of discharge while allergies are more likely to cause itchiness and watering.

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Treatments: What to do if you have pink eye

Benner recommends people visit an eye doctor if the their eyes become inflamed or red and they have other symptoms such as discharge, itching or discomfort.

Doctors will prescribe treatments based on the type of infection:

• Bacterial pink eye is typically treated with eye drops containing antibiotics.

• Eye drops can also alleviate the itchiness and puffiness cause by allergies.

• For viral infections, a person might get comfort from a cool washcloth or artificial tears. Symptoms from most viral infections go away in seven to 10 days, Benner said.

If you suspect pink eye, Benner recommends being careful about personal hygiene:

• Avoid touching your eyes.

• Wash your hands regularly with soap and water.

• Don't share personal items such as eye makeup with others.

Ken Alltucker is on Twitter at @kalltucker, or can be emailed at alltuck@usatoday.com

This article originally appeared on USA TODAY: COVID variant Arcturus pink eye: Symptoms and treatment, explained