The World Health Organization (WHO) has identified a new “stealth omicron” strain, feared to be more transmissible and evasive than the previous variants.

Officially named BA.2.75 and nicknamed “Centaurus,” the new subvariant has been found in 10 countries, including Australia, Canada, Japan, New Zealand, Germany, the United States and the United Kingdom.

The subvariant has recently risen to prominence in India, where it’s competing with omicron. But the WHO has not named it a variant of concern yet.

In an update released via Twitter, WHO officials said initial data on the subvariant is currently limited. Its overall transmissibility, severity, and potential for immune evasion are currently unknown.

Dr. Eric Topol, a professor of molecular medicine at Scripps Research and founder and director of the Scripps Research Translational Institute, pointed out on Twitter that the subvariant has “eight mutations beyond BA.5, many in the N-terminal domain, which could make immune escape worse than what we’re seeing now.”

Topol also quoted Dr. Ulrich Elling, a molecular biologist, who said the U.S. might “have to prepare” for the Centaurus wave because he didn’t “like the observed mutations.”

“The number of eight additional mutations in BA.2.75 is remarkable. Delta had eight in spike in total. Three mutations can make a huge difference (BA.5). Thus the 11 mutations distinct between BA.5 and BA.2.75 could allow for yet another wave as BA.5 immunity might not protect,” tweeted Elling.

WHO chief scientist Dr. Soumya Swaminathan said more research is needed to better understand its transmissibility and severity. According to her, it’s still too early to know if Centaurus has properties of additional immune invasion.

“We don’t know that, so we have to wait and see,” she noted.

The omicron subvariant is currently dominant in the U.S., estimated to have caused nearly 54% of infections in the U.S. last week, according to data released by the U.S. Centers for Disease Control and Prevention.

In a post made last week, Dr. Topol called omicron the “worst version of the virus that we’ve ever seen” due to its enhanced transmissibility.