Health experts still learning about omicron subvariant, now dominant in Northeast

As a version of COVID-19’s omicron variant —the XBB.1.5 subvariant — grows more prevalent in some parts of the U.S., health experts say it likely escapes immune protection better than previous mutations, though it is still unclear whether it causes more severe illness. 

More than 80 percent of coronavirus cases in the Northeast are now due to XBB.1.5. 

According to health authorities, XBB.1.5 appears to be the most transmissible subvariant of omicron that has been detected yet. The bivalent COVID-19 vaccine and antiviral treatments like Paxlovid and molnupiravir are still believed to be effective at treating the strain, though they may not be as effective when compared to previous mutations.

Physicians from across the Northeast who spoke with The Hill said they have not noticed a marked difference in disease severity among their recent COVID-19 patients.

Bernard Camins, medical director for infection prevention at the Mount Sinai Health System in New York, said the proportion of patients with illness severe enough to require an intensive care unit stay is the same as with previous variants.

Camins said a recent labor dispute with nurses in the Mount Sinai Health System presented more of a disruption to his hospital than the increase in COVID-19 cases that occurred after the holidays.

“The presentation is for the most part the same. Maybe they’re not presenting as ill, but we are still seeing plenty of ill patients and we are still certainly seeing patients that die,” Ulysses Wu, chief epidemiologist for Hartford Healthcare in Connecticut, said.

Wu said XBB.1.5 does not appear to be more lethal and noted that any time more cases of COVID-19 are seen, morbidity and mortality will increase in turn.

“The reality is, [people] shouldn’t be any more concerned about the new variants because they should be just as concerned about this variant as they were about the previous variant. They’re all equally dangerous to a certain extent,” said Wu.

Shira Doron, chief infection control officer for Tufts Medicine in Boston, said the new dominant strain was “not really such a big deal” in her area. According to Doron, her hospital has seen a “modest” increase in new admissions, though she noted that most of the patients who test positive for coronavirus are not being admitted due to a COVID-19 infection but because of another ailment.

“I do feel like we’re in a really good place. I want to make sure that we don’t lose access to testing, we don’t lose access to treatment,” Doron said, adding that there is still work to be done when it comes to ensuring access to effective medications to treat COVID-19.

At the start of January, the Food and Drug Administration said it did not anticipate Evusheld, the preventative coronavirus monoclonal antibody treatment, to be effective against XBB subvariants. The treatment was authorized for people who likely would not have developed strong enough immune responses from the COVID-19 vaccines.

Jo-Anne Passalacqua, an infectious disease specialist at St. Vincent’s Medical Center in Connecticut, said she doesn’t think there is any reason to believe XBB.1.5 represents a change in disease severity.

“The folks that we’re seeing that are very ill with COVID are similar to the people that were very ill with COVID before. They’re either frail elderly or they’re people with underlying heart or lung disease, you know, or some or some underlying immune compromise,” she said.

While severity does not seem to be worsening, Passalacqua cited some concerns when it came to the newest mutation. Recent studies, such as one conducted by researchers at the University of Texas, found the bivalent COVID-19 booster had a reduced efficacy against omicron subvariants like BQ.1.1 and XBB.1, from which the strain widely circulating in the Northeast descends.

“I think that information is very concerning because the public, the world, has returned in many respects to life as we knew it,” she said, noting families gathered and people traveled over the holidays as they did in pre-COVID times.

“And that might be OK if you’re a reasonably healthy person who, if they get COVID and it becomes a little more severe, can call your doctor and get some Paxlovid. But that’s not going to be OK for somebody who has heart disease, lung disease, is frail and elderly. For those folks, that infection may result in death.”

Health care providers who spoke with The Hill all encouraged people to get vaccinated if they aren’t already.

Frederic Bushman, who oversees the Bushman Lab, a microbiology research lab at the University of Pennsylvania’s Perelman School of Medicine, said that even though vaccines may be less effective against a particular subvariant, people are still better off immunized.

“Our countermeasures are getting better and better. Vaccines still work. Go out and get vaccinated. Maybe they work a little less well with the new variant, but they still work.”

Passalacqua emphasized that regardless of what variant is circulating, people should get “back to some basics” when it comes to limiting the spread of infectious illnesses. She urged people to make use of simple measures like hand washing, wearing masks in crowded spaces and staying home if you are feeling ill.