What to Know About Arcturus, the Latest COVID Variant

Experts say the strain, formally known as XBB.1.16, could cause a summer surge

By Rachel Nania, AARP | May 01, 2023

Health officials and virus experts are keeping a close eye on a new subvariant of omicron that’s been reported in nearly 30 countries and is growing its presence in the U.S.

Nicknamed Arcturus, and technically referred to as XBB.1.16, the strain is behind an estimated 12 percent of new COVID-19 cases in the U.S., up from 7.4 percent the previous week, data from the Centers for Disease Control and Prevention (CDC) shows. Judging by patterns seen in other countries — especially India, where XBB.1.16 is more widespread — Matthew Binnicker, director of the Clinical Virology Laboratory at Mayo Clinic, predicts the subvariant will outpace the current dominant strain in circulation (XBB.1.5) and take the lead by summer.

What this means is that we could see another surge of infections over the coming months, Binnicker says. However, he suspects this new wave will not be as bad as previous ones, like when omicron and delta first burst onto the scene. 

A big reason: “There is a high level of existing immunity in the population, either [from] prior infection or from vaccination,” Binnicker says. This immunity reduces the risk of reinfection, or severe illness if a person is infected, though the CDC notes that protection does wane some over time.

More recently, health officials gave the all-clear for adults 65 and older and immunocompromised individuals to get a second bivalent booster to restore diminished protection. These updated vaccines, which first became available in September 2022, target both the original strain of the coronavirus and two omicron strains no longer in circulation. Data show the bivalent vaccines have been effective against other omicron subvariants that have emerged, and Binnicker predicts that will hold true with XBB.1.16.

Does the new subvariant cause new symptoms?

So far, there’s no sign that this subvariant causes people to get sicker, officials with the World Health Organization (WHO) say. In the U.S., hospitalizations and deaths from COVID-19 have been steadily declining since winter, federal data shows, though they remain highest among the older adult population.

However, symptoms may differ with XBB.1.16. Conjunctivitis, or pink eye, has been linked with COVID in the past, but Binnicker says some doctors in India have noted it’s popping up more often in people infected with XBB.1.16, especially in children. Some people may also experience higher fevers, he adds.

“So those are two things for physicians to keep an eye on as we start to see an increase in prevalence here in the U.S.,” Binnicker says.

This time of year, the red, itchy eyes that accompany conjunctivitis could easily be blamed on seasonal allergies. Conjunctivitis can also be a symptom of other viral infections, such as adenovirus, which is spiking in the U.S. right now, national surveillance data shows. Binnicker says this underscores the importance of getting tested for COVID-19 if you experience any symptoms related to a coronavirus infection. With a positive test, you could be eligible for antiviral treatments that can significantly reduce your risk of severe COVID-19 complications.

Another tip: Stay vigilant. WHO Director Tedros Adhanom Ghebreyesus said in a recent media briefing that the emergence of XBB.1.16 illustrates that the “virus is still changing and is still capable of causing new waves of disease and death.”

Rachel Nania writes about health care and health policy for AARP. Previously she was a reporter and editor for WTOP Radio in Washington, D.C. A recipient of a Gracie Award and a regional Edward R. Murrow Award, she also participated in a dementia fellowship with the National Press Foundation.

From What to Know About Arcturus, the Latest COVID Variant, by Rachel Nania, AARP, May 01, 2023,, Copyright 2023 by Rachel Nania, AARP.
Reproduced, by ARCIL, Inc. for educational purposes.


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