What to know about XBB.1.16, a new Omicron variant on the WHO’s radar

There’s a new variant of the coronavirus that infectious disease experts and public health officials are keeping a close eye on. XBB.1.16, also known as Arcturus, is an Omicron subvariant that appears to be more transmissible and has fueled a recent surge of COVID-19 cases in India. While the variant is circulating at low levels in the U.S., health officials are closely monitoring it.

The World Health Organization warned about XBB.1.16 last month and labeled it a “variant of monitoring,” a designation that isn’t as serious as a “variant of interest.” However, that status could change if the variant shows signs of increased transmissibility or virulence, or is able to evade antibodies, the WHO noted.

XBB.1.16 has now been detected in at least 29 countries, including the U.S. and it is expanding its reach fairly quickly. In late February, XBB.1.16 accounted for only 0.21% of all COVID-19 cases worldwide. A month later, that had increased to 3.96%, according to the WHO’s latest figures.

The Centers for Disease Control and Prevention began reporting cases of XBB.1.16 last Friday. According to the latest CDC data, the variant now accounts for 7% of new COVID-19 cases nationwide.

Here’s what to know about “Arcturus,” or XBB.1.16

What is XBB.1.16? Is it more dangerous?

XBB.1.16 is a sublineage of the Omicron variant that’s similar to XBB.1.5, the strain that has dominated infections in the U.S. since January. But XBB.1.16, the WHO noted, has a mutation in the virus’s spike protein that has been associated with increased transmissibility and potentially a higher degree of infection. However, some experts have said that while it looks like it could spread more quickly and lead to more cases, it doesn’t appear to cause more severe disease.

In India, the variant has led to a surge in COVID-19 cases in recent weeks. On Tuesday, India's Health Ministry reported 61,233 COVID-19 cases, which is a notable increase from the 15,208 cases that were reported on March 31. However, hospitalizations have not surged significantly.

“I doubt it will lead to too many new hospitalizations or deaths,” Dr. Monica Gandhi, an infectious disease specialist and a professor of medicine at the University of California, San Francisco, told Yahoo News. “I was just in India. ... There was an increase in cases but not an increase in hospitalizations,” she added.

Gandhi explained that the coronavirus won’t be fully eradicated, so it will continue to evolve and new forms of it will continue to emerge. However, she said new variants won't necessarily become more dangerous. She added that most of the population has immunity from either the vaccines, infection, or both, and that will continue to protect most individuals against the worst outcomes of the disease.

“I think this is where we are. We're gonna have to live with this [virus] and we're going to see cases go up and down if we get a new subvariant that's more transmissible, but hopefully, it will not lead to an increase in severe disease,” Gandhi said.

Does the new variant cause different symptoms?

According to anecdotal reports coming from India and other parts of the world, including the U.S., XBB.1.16 may cause a new COVID-19 symptom not seen with previous coronavirus strains. Some doctors have said the new variant seems to be causing conjunctivitis, often called pink eye, in children and adolescents.

In a recent tweet, Vipin M. Vashishtha, an Indian pediatrician who is also a member of the WHO's Vaccine Safety Net program, said he had started to get pediatric COVID-19 cases again, and more children who are sick with XBB.1.16 are experiencing “itchy conjunctivitis with sticky eyes.”

The Mayo Clinic also reported on Thursday that experts are seeing the same eye symptoms in young patients who are sick with COVID-19.

Dr. Michael Chang, a pediatric infectious diseases expert at UTHealth Houston and Children's Memorial Hermann Hospital, told Yahoo News that many things can cause pink eye. He said that at the moment there’s not enough evidence to say that the new COVID variant is causing conjunctivitis in children.

“We don't have the context of whether they're seeing that in some of the regions in India. We know their COVID cases are going up, and presumably, these kids are testing positive for COVID, but we don't know if they're testing positive for anything else either,” Chang said.

He explained that other viruses can cause conjunctivitis. Adenovirus, which can cause a mild cold or flu-like illness and can be easily confused with COVID-19, is one of them. Cases of adenovirus tend to increase in the spring and summer, and Chang said doctors in the U.S. are seeing more of it these days.

“We are seeing adenovirus circulating, so even if COVID cases go up, unless you're doing testing for both COVID and adenovirus, which most people aren't … it may be difficult [to determine] what's causing your pink eye.”

Are our COVID-19 vaccines effective against XBB.1.16?

When a new variant of the coronavirus emerges, one concern that arises is whether our current vaccines will protect us against that strain.

It is too early to know how well the COVID-19 vaccines neutralize XBB.1.16. However, some experts believe the shots should remain effective at preventing severe illness and death, even if XBB.1.16 is found to be able to evade antibodies from vaccines. Gandhi explained that this is because, aside from antibodies, there are other parts of the immune system that are activated with vaccination and infection, such as B cells and T cells, which can also offer long-lasting protection against the virus.

Although there’s no reason to be concerned right now, Gandhi said that whenever there’s a new, more transmissible variant, people who are older and those who are immunocompromised are at the highest risk for complications. She urged those groups to stay up to date with vaccination, particularly getting the bivalent booster if they haven’t received it yet.

“If you're in an older or vulnerable group, if you are someone who is over 65 or on immunosuppressants or have multiple comorbidities, just go out and get a booster,” she said.

On Tuesday, the FDA authorized a second dose of the bivalent COVID-19 vaccine for seniors and immunocompromised people. The CDC’s Advisory Committee on Immunization Practices — a group of outside experts who advise the agency on vaccines — is scheduled to meet on Wednesday to discuss the strategy. If these experts recommend the shots, CDC Director Dr. Rochelle Walensky is likely to sign off on their use and they could become available as early as this week.

Cover thumbnail photo: Getty Images