As the U.S. continues to battle the spread of the highly-transmissible omicron subvariant BA.5, a new mutant that could be competitive with the super contagious strain is making its way into the U.S.
And some health officials expect cases will continue to grow.
Here's what we know so far about the BA.2.75 subvariant:
What is BA.2.75 and what makes it concerning?
Scientists say the variant – called BA.2.75 – may be able to spread rapidly and get around immunity from vaccines and previous infection. It’s unclear whether it could cause more serious disease than other omicron variants, including the globally prominent BA.5.
“It’s still really early on for us to draw too many conclusions,” said Matthew Binnicker, director of clinical virology at the Mayo Clinic in Rochester, Minnesota. “But it does look like, especially in India, the rates of transmission are showing kind of that exponential increase." Whether it will outcompete BA.5, he said, is yet to be determined.
Still, the fact that it has already been detected in many parts of the world even with lower levels of viral surveillance “is an early indication it is spreading,” said Shishi Luo, head of infectious diseases for Helix, a company that supplies viral sequencing information to the U.S. Centers for Disease Control and Prevention.
“It’s still really early on for us to draw too many conclusions,” said Matthew Binnicker, director of clinical virology at the Mayo Clinic in Rochester, Minnesota. “But it does look like, especially in India, the rates of transmission are showing kind of that exponential increase."
"It's about a quarter of the cases right now in India. It's sort of competing with BA.5 there," Chicago Department of Public Health Commissioner Dr. Allison Arwady said. "It does look to be contagious, at this point doesn't look to be more serious, but we're still learning. It's not been named a variant of concern at this point. So we're watching it just like we watch other variants."
Another concern is that the genetic tweaks may make it easier for the virus to skirt past antibodies — protective proteins made by the body in response to a vaccine or infection from an earlier variant.
It may take several weeks to get a sense of whether the latest omicron mutant may affect the trajectory of the pandemic. Meanwhile Dr. Gagandeep Kang, who studies viruses at India’s Christian Medical College in Vellore, said the growing concern over the variant underlines the need for more sustained efforts to track and trace viruses that combine genetic efforts with real world information about who is getting sick and how badly. “It is important that surveillance isn’t a start-stop strategy,” she said.
Arwady noted that Chicago and the Midwest are currently in a wave of BA.4 and BA.5 subvariants, but uncertainty surrounding even newer variants continues to spark concerns.
"Variants continue to worry people and they should worry people," Arwady said. "Every time we have a new variant that emerges, it's the part that is the least control with COVID. If the COVID virus didn't mutate at all from here on out, I would have no questions about what we do to sort of get us out of COVID. The problem is, because it keeps mutating, because we keep seeing new variants - every time that happens in some way the virus is changing to be more contagious, which is most of what we've seen, but there's the potential for it to become, you know, more serious, there's the potential for it to become less serious, but you just don't know for sure. And that uncertainty is part of what makes it very hard to fully be able to predict the future."
Where has the BA.2.75 variant been detected?
The latest mutant has been spotted in several distant states in India, and appears to be spreading faster than other variants there, said Lipi Thukral, a scientist at the Council of Scientific and Industrial Research-Institute of Genomics and Integrative Biology in New Delhi. It’s also been detected in about 10 other countries, including Australia, Germany, the United Kingdom and Canada. Two cases were recently identified on the West Coast of the U.S., and Helix identified a third U.S. case last week.
Arwady said that while the new variant has so far been detected in some cases in the U.S. and around the world "we probably will see more cases."
"Whether it'll compete with BA.5 we just don't know," she said.
Do vaccines work against BA.2.75?
But experts say vaccines and boosters are still the best defense against severe COVID-19. In the fall it’s likely the U.S. will see updated formulations of the vaccine being developed that target more recent omicron strains.
“Some may say, ‘Well, vaccination and boosting hasn’t prevented people from getting infected.’ And, yes, that is true,” he said. “But what we have seen is that the rates of people ending up in the hospital and dying have significantly decreased. As more people have been vaccinated, boosted or naturally infected, we are starting to see the background levels of immunity worldwide creep up.”
Arwady added that vaccinations remain critical even as spread continues.
"I don't love BA.4, BA.5 and that it is the most contagious yet. I don't love the BA.2.75 that we're just keeping an eye on. But most importantly we're not seeing any change at this point in terms of protection against severe illness or major change and severity," she said. "And while that remains true, it's about getting up-to-date with your boosters, wearing your masks indoors, especially if you're in settings where you don't know a vaccine status, you know, testing, isolating, quarantining... there's not magic to this, but we do have the tools."
Luo said BA.2.75 is another reminder that the coronavirus is continually evolving – and spreading.
“We would like to return to pre-pandemic life, but we still need to be careful,” she said. “ We need to accept that we’re now living with a higher level of risk than we used to.”