A new variant of the coronavirus has emerged in the U.K., but it’s too soon to know whether it should be cause for concern.
Called XE, it is a combination of two versions of omicron, named BA.1 and BA.2. It’s common for viruses to recombine, experts said.
Since XE was identified in early January, it has infected about 600 people in the U.K.. It’s not clear whether XE is more contagious than BA.2, and there is no indication it can cause more severe disease.
XE “has shown a variable growth rate and we cannot yet confirm whether it has a true growth advantage.” Susan Hopkins of the U.K. Health Security Agency said in a statement. “So far there is not enough evidence to draw conclusions about transmissibility, severity or vaccine effectiveness.”
Dr. Jeremy Luban, an infectious disease specialist at the University of Massachusetts Medical School, said he’s watching XE but is not worried yet.
“XE has a powerful combination of all these variants of coronavirus. Should it spread rapidly through the U.S. at some point, we would be concerned,” Luban said.
Dr. William Schaffner, an infectious disease specialist at the Vanderbilt University School of Medicine in Nashville, Tennessee, said there’s no reason to panic.
“There’s still a lot we don’t know about XE,” he said. “XE could surprise us, so we have to wait to see how severe it will be.”
He said he’s more concerned about BA.2, which accounts for 72% of COVID-19 cases in the USA and is the dominant variant worldwide.
BA.2 has led to several outbreaks around the world but is not driving up cases substantially in the USA. Cases dropped 4% compared with a week earlier, and hospitalizations and deaths are both down more than 16%, Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention, said Tuesday.
What exactly is XE?
The British Health Security Agency confirmed 637 cases of XE, the earliest on Jan. 19.
As a mix of two variants, XE is what’s called a recombinant virus. This mixing of viral DNA is so common that XE is the fifth recombinant virus involving omicron.
The British Health Security Agency identified XD and XF as combinations of delta and omicron BA.1.
In the U.K., 38 cases of XF have been identified, all before mid-February, and there is no evidence that this version of the virus is being transmitted within the country.
Forty-nine cases of XD have been reported in global databases, the majority in France.
Infectious disease experts worry that a variant will develop that’s as contagious as BA.2 and as lethal as delta, but all the omicron-related variants have caused less severe disease.
The vaccines have provided good protection from severe illness and death from the variants, though a third vaccine dose is needed to provide the same level of protection against omicron as against earlier variants.
Because of their unpredictability and dangerous potential, variants will continue to pose a threat to the world’s “return to normalcy,” Schaffner said.
“This is our new reality, variants popping up everywhere because fortunately, we are detecting them,” he said. “The more we can find, the more we can study and contain.”
Contributing: Karen Weintraub
