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Officials are keeping a close eye on the latest COVID-19 variants as the summer continues. Alexi Rosenfeld/Getty Images
  • Officials are keeping a close eye on the latest COVID-19 subvariant.
  • They say Omicron BA.2.75 may be the most contagious variant yet with the ability to bypass previous immunity.
  • So far, it’s been most prevalent in India, although it has shown up in about a dozen countries, including the United States.
  • Experts say the new information reinforces the notion that people should continue to get vaccinated and boosted and those at an elevated risk should consider wearing a high-quality mask when indoors and in crowded outdoor venues.

The numbers make it hard to keep up.

Right now, the White House reports that the top subvariants causing an increase in COVID-19 cases are Omicron BA.4 and BA.5.

Together, they account for 80 percent of new COVID-19 cases in the United States, with BA.5 responsible for the majority.

However, experts are now warning there’s a new subvariant on the horizon that is worrisome. It’s BA.2.75, or as Twitter has nicknamed it, “Centaurus”.

“This is another variant, descending from the BA.2 version of Omicron,” says Dr. Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security and an assistant professor at the Johns Hopkins Bloomberg School of Public Health in Maryland.

“I like to refer to it as a grandchild of the original Omicron strain,” adds Matthew Binnicker, Ph.D., a microbiologist and director of clinical virology at the Mayo Clinic in Minnesota.

The concern is that BA.2.75 is highly infectious and it may be able to bypass previous immunity, although mask wearing and vaccinations remain important preventive measures to ward off serious illness.

Officials at the World Health Organization (WHO) say they have been monitoring the growth of Omicron 2.75.

The agency says it is spreading rapidly in India but has also been detected outside that country.

According to tracking data from GISAID, which is compiled by Raj Rajnarayanan, PhD, an assistant dean of research and an associate professor at Arkansas State University, the subvariant has been detected in more than a dozen other countries, including the United States.

A handful of cases identified as BA.2.75 has been detected in California, Washington, Illinois, New York, North Carolina, Texas, and Wisconsin.

However, experts say we aren’t doing enough testing and surveillance to know just how prevalent it might be.

“It’s probably a combination of two things… BA.2.75 likely isn’t prevalent here yet. That being said, it definitely could become prevalent in the coming weeks or months” Binnicker told Healthline.

“Second, the amount of samples that are being tested in laboratories and then sequenced is much lower today than it was in January and February” he added. “That’s because many people are taking home tests and not even seeking clinical lab tests.”

WHO officials have included BA.2.75 under the Omicron sublineages it considers “variants of concern” and is also monitoring it.

Experts say the subvariants have mutations in their spike proteins. That’s the part of the virus that sticks out from the surface and binds to the host cells and allows the virus to burrow into the cells.

“BA.2.75 has additional mutations on top of what we’re seeing in BA.5, so even more changes in that spike protein,” said Binnicker.

“People who look at where the mutations are and that spike protein are concerned that it will be even better at evading any pre-existing immunity,” he said.

Still, some experts say it’s too soon to know exactly what this subvariant might do.

“I think it is too early to say that this is worrisome because it is unclear how this variant will fare when it has to compete with BA.5,” Adalja told Healthline.

Experts say mask-wearing and vaccinations are still effective measures you can take.

“We’ve learned that vaccination or prior infection doesn’t protect you, especially long term from getting infected again, or being infected for the first time,” Binnicker said.

“But even those who have been vaccinated and come down with a symptomatic illness, what we are seeing is an overall trend of lower numbers of people ending up in the hospital” he added. “Lower numbers of people are coming down with severe disease and ending up in intensive care on ventilators and dying.”

“The goal is to make sure that your bout with it is mild by being vaccinated and having a plan to use Paxlovid and monoclonal antibodies if you are at high risk,” Adalja added.

Vaccine makers are working on an updated version that is Omicron-specific might be ready for the fall, but Binnicker notes there may not be time to include BA.2.75.

“My initial thought is that the vaccine manufacturers are already working on updates to the vaccine formulation, likely including some of the earlier strain of Omicron,” he said. “I’m not sure the BA.2.75 is going to make it into the update formulation. Because it’s just now hitting the scene. And there’s probably studies already ongoing… safety and efficacy studies… for the updated vaccines.”

“But if we do have an updated formulation that includes some of the earlier Omicron subvariants, it should really help in terms of greater protection, even against some of those strains that are just now emerging,” he added.