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Omicron XE: Everything We Know About The New Hybrid COVID-19 Variant


Dr. Katie Spalding

Katie has a PhD in maths, specializing in the intersection of dynamical systems and number theory.

Freelance Writer


Image credit: Mayboon/

Another day, another COVID-19 strain on the scene. It seems like not even two weeks ago that we were reporting the discovery of a new Delta-Omicron hybrid variant, and now it’s already old news, as the World Health Organization (WHO) warns of its cousin, XE.

“The XE recombinant (BA.1-BA.2), was first detected in the United Kingdom on 19 January and [more than] 600 sequences have been reported and confirmed since,” explains a report from the Organization, originally released last Tuesday.


“Early-day estimates indicate a community growth rate advantage of ~10 percent as compared to [Omicron 'stealth' subvariant] BA.2,” the report continues. “[H]owever this finding requires further confirmation.”

Like the Delta-Omicron variant, this new strain of COVID-19 is what’s known as a “recombinant”: a new virus made from the combination of two variant viruses. It’s what you’d get if two COVID-19 lineages had a baby, rather than just mutating randomly like they did more at the beginning of the pandemic. Unfortunately for journalists – though no doubt to the relief of many experts in the field – the XE strain is a recombinant of the Omicron variant and the Omicron subvariant BA.2. That makes any potential portmanteau names, like its predecessor’s “Deltacron,” unacceptably confusing – hence “XE”.

As it stands, we don’t know a whole lot about the new XE lineage, which is why the WHO has stated that the new recombinant “belongs to the Omicron variant until significant differences in transmission and disease characteristics, including severity, may be reported.”

Meanwhile, public health authorities in the UK, where the recombinant was first detected and currently accounts for fewer than 1 percent of genome-sequenced COVID-19 cases, are continuing to monitor the spread of the XE strain.


“This particular recombinant … has shown a variable growth rate and we cannot yet confirm whether it has a true growth advantage,” said Professor Susan Hopkins, Chief Medical Advisor for the UK’s Health Security Agency. “So far there is not enough evidence to draw conclusions about transmissibility, severity or vaccine effectiveness.”

“UKHSA will continue to monitor the situation closely as a matter of routine, as we do all data relating to SARS-CoV-2 variants both in the UK and internationally,” she added.

While the true impact of the XE variant is yet to be seen, experts say we probably shouldn’t panic too much about it.

“Right now, there's really no public health concern,” epidemiologist and chief innovation officer at Boston Children's Hospital Dr. John Brownstein told ABC News. “Recombinant variants happen over and over. In fact, the reason that this is the XE variant recombinant is that we've had XA, XB, XC, XD already, and none of those have turned out to be any real concern.”


“It's possible it may be more transmissible, but that doesn't necessarily mean it's more severe,” he said. “And given the sheer number of infections we've already seen with omicron, it's really unclear whether even being slightly more transmissible means we'll see any impact of this variant whatsoever.”

Indeed, the WHO confirmed last week that there’s no evidence yet that the new recombinant will turn into a variant of concern – and while the XE strain has yet to be found in the US, the message for anybody worrying about this new recombinant on the block is the same as it ever was.

“Being vaccinated and boosted, as well as practicing good hygiene and following public health recommendations all help to drive transmission down in the community,” Brownstein told ABC. “When we have uncontrolled spread, that's when the virus is given chances to mutate.”


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