New COVID Variants BQ.1, XBB, and More Could Fuel Surge

group of diverse people wearing masks in public

group of diverse people wearing masks in public


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Fast Facts

  • New Omicron subvariants are gaining traction in the U.S. and around the world, and they are likely more transmissible than other Omicron variants. 
  • These new variants can evade the body’s antibody immune response, which leaves people vulnerable to breakthrough cases after vaccination or prior infection.
  • Experts say bivalent boosters are still effective at preventing severe disease from newer Omicron subvariants.

Omicron subvariants BA.4 and BA.5 have dominated COVID cases in the U.S. since early July, but new lineages are picking up steam—and they have some experts concerned. 

The most recent data from the Centers for Disease Control and Prevention (CDC) show that four newer variants of concern are making headway in the U.S.: BA.4.6, BQ.1.1, BQ.1, and BF.7—all of which are part of the Omicron lineage.

To a lesser extent, Omicron subvariants BA.2.75.2, BA.2.75, and BA.4 are still being detected in the country. 

XBB—and its sibling XBB.1—is also lurking in the background for the U.S. First detected in India in August, XBB now accounts for over half of all COVID cases in Singapore, according to its Ministry of Health, and has been detected in more than 17 countries, including the U.S., though the CDC’s variant surveillance system has yet to pick it up.

The BQ.1 and BQ.1.1 subvariants in particular—which currently make up more than 11% of all COVID cases in the U.S.—are “pretty troublesome,” according to Anthony Fauci, MD, chief medical advisor to President Biden. He recently told CBS News that the country must still watch out for these and other emerging variants. 

Here’s what we know about the new variants so far, how they might compare to other Omicron variants, and what to do to stay safe in the face of a potential fall and winter COVID surge. 

New and Emerging Omicron Subvariants, Explained

All of the subvariants in question are derived from other, previously known Omicron variants—meaning they all share some similarities to each other and the Omicron variants that are circulating and have circulated in the past. 

BA.4.6, for example, descends from BA.4; BF.7, on the other hand, is an offshoot of BA.5—as are BQ.1 and BQ.1.1

“BQ is actually a BA.5 variant,” Andrew Pekosz, PhD, a virologist at the Johns Hopkins Bloomberg School of Public Health, told Health. “Here in the U.S., all the variants that are circling—BQ.1.1 I guess is the biggest or the most talked about one now—they’re all derived from either the BA.5 or the BA.4 variants. They’ve picked up a few mutations that help them evade some of the infection or vaccine-induced immunity.” 

The XBB variant came about in similar fashion—it’s related to the BA.2 variant, which was dominant in the U.S. last spring.

Though these two variants mutated from different Omicron strains, BQ.1.1 and XBB have picked up some of the same mutations—a process called convergent evolution, according to Pekosz. This means the two resemble each other fairly closely, even though they exist on different branches of the Omicron family tree. 

Mutations Making the Virus More Transmissible

Each time a new variant starts to gain traction, it’s largely because it’s more transmissible in some way than previous COVID strains—and these newer subvariants are no exception. 

Though they’re not sentient, viruses aim to spread and replicate as much as possible, Otto Yang, MD, associate chief of infectious diseases and professor of medicine at the David Geffen School of Medicine at the University of California, Los Angeles, told Health. BQ.1.1, BQ.1, and XBB are just the newest iterations of this story that we’ve been seeing play out throughout the COVID pandemic.

“We're seeing the virus optimize itself to spread as efficiently in humans as possible,” Dr. Yang told Health. “So that's the main reason that we're seeing all these variants coming up, is that the virus is continuing to be selected for better spread in humans because that's to its evolutionary advantage.” 

This is precisely what worries some experts. These new variants spread among people very quickly, and may be able to get past antibodies which would otherwise stop an infection. 

In Singapore, the XBB variant grew from 22% to 54% of total cases in just one week, which gives a window into just how transmissible these strains could be. And researchers from Peking University in China, in a preprint study that has not yet been peer reviewed, found that XBB, BQ.1.1, and a few other variants were the most immune evasive of those variants tested.

“If you can avoid the immunity that many people have in a population, those people become targets for your infection again, and they become susceptible to reinfection,” said Pekosz. “That can increase case numbers because the virus is evading the immunity that’s protecting people from other variants.”

More specifically, the BQ.1.1, BQ.1, and XBB variants seem to be specifically evading antibodies, Dr. Yang explained. 

“​​Even though you're vaccinated, or even though you had COVID before, you can get reinfected,” he said. “You can get infected with these strains more easily because the antibodies don't protect you.” 

But antibodies are just half of our bodies’ response to pathogens, Dr. Yang added—the body’s T cells will still be able to recognize the spike proteins on these mutated viruses and destroy them. 

“Even though the viruses may spread more easily, people that are up to date on their vaccines, or recently infected with another strain should still have excellent protection from severe illness or death, as long as their immune system is relatively normal,” Dr. Yang said. 

Another note of good news is that, despite their increased transmissibility, these new variants don’t seem to be any more deadly than other Omicron variants. 

Even with XBB as the majority variant, Singapore’s hospitalizations have remained proportional to the number of current infections, and cases of severe illness are still low. There have been no reports so far of new or particularly dangerous symptoms, Pekosz added. 

There’s less available data about the severity of BQ.1 and BQ.1.1 here in the U.S., said Pekosz, so it may just be a waiting game for the time being to see if hospitalizations or deaths go up.

Omicron Subvariants: Why Are There So Many, What Can They Tell Us?

Cases Will Likely Rise, But Omicron Boosters Are Still Effective

These variants have just recently started making headlines, so it may be too early to predict how COVID might shape our fall and winter. But a winter surge is expected, Pekosz said, so cases will certainly be going up in the next few weeks and months—it’s just unclear how much. 

“It's really the next couple of weeks that are really going to tell us how things are going to be turning, in terms of how sharply up these case numbers go,” said Pekosz.

Luckily, the new Omicron-specific COVID boosters should still be effective, since the newer subvariants don’t differ too drastically from the Omicron strains used to make the shots. While breakthrough infections may still occur, the boosters should be able to prevent severe illness, according to Dr. Yang and Pekosz.

Monoclonal antibody treatments—used to treat people who get sick with COVID—may be another story. 

“This is a big concern [particularly with] the XBB and BQ.1.1. Some of these mutations that all these Omicron lineages are picking up knock out the last of our monoclonal antibody treatments,” said Pekosz. “It leaves some of the more vulnerable portion of the population without a viable treatment option going forward.”

Though antibody treatments may not be as effective against BQ.1.1 and XBB, other antiviral treatments, such as Paxlovid, should still offer some protection, Dr. Yang explained. 

The other bit of good news is that cases of these newer subvariants do not seem to be exploding in the same way that the numbers were when Omicron first burst onto the scene in December 2021 and January 2022, said Pekosz. 

“We should be monitoring this. But it doesn't come to a level like Omicron did when it emerged,” he explained. “We almost immediately saw all the signs that the virus could evade immunity and spread easily, and therefore we knew something bad was coming right around the corner.”

The best thing to do, Dr. Yang and Pekosz agreed, is to stay up to date on your vaccinations—even if it doesn't prevent you from getting COVID, it will ensure that your T cells are in good shape to protect you from severe illness. Staying in the know and having a plan for what to do if you or a loved one gets COVID is also a good idea.

“We're not going to get rid of this pandemic by forgetting about it,” Pekosz said. “We're going to minimize its effect by really continuing to be proactive, continuing to fight against it using the tools that we've developed over the past several years.”

COVID-19 Boosters Are Being Updated To Target Omicron Subvariants—Here’s Why

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