The Omicron sub-variant XE is the latest in a line of coronavirus strains that have piqued people’s curiosity and raised concerns about increased transmissibility or severity.
The novel coronavirus, which causes COVID-19 disease, has developed many variants in the last two years through evolution. This evolutionary process takes process in all viruses and is in itself not a form of concern.
What are variants and sub-variants?
All viruses evolve and acquire mutations, which lead to the formation of its many “variants”.
These “variants” further split and branch to form their sub-lineages called “sub-variants”. The Delta variant that was behind India’s deadly second wave is known to have up to 200 sub-variants.
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Not all mutations and variants (and sub-variants) these mutations lead to are concerning. However, some mutations do make the virus better at infecting people or in making them more sick.
What is Omicron sub-variant XE?
The Omicron variant has three sub-variants – BA.1, BA.2, and BA.3.
The XE is a “recombinant” of BA.1 and BA.2 sub-variants, which means it is a mixture of these two and contains both of their mutations. This is why many early reports referred to XE as the “Frankenstein” variant – a reference to Frankenstein's Monster, which was made by mixing several body parts in a famous novel.
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The XE was first discovered in the United Kingdom in January 2022. Around 600 cases have since been discovered across the world.
What’s known about its symptoms, transmissibility, and severity?
The XE is 10 per cent more transmissible than Omicron’s BA.2 sub-variant, which itself was 80 per cent more transmissible than the BA.1 sub-variant, according to the World Health Organization.
However, the XE so far does not appear to be very different from other Omicron sub-variants.
Experts have highlighted that XE has emerged very quickly after previous Omicron waves and it means that this new sub-variant will face the wall of natural immunity from recoveries from earlier Omicron infections. Increased vaccination across the world is also believed to blunt any impact that XE might have had, combined with the natural immunity.
The XE does not appear to have any special symptoms. Reports from the UK, where it first emerged, have noted cold as the most common symptom. Other symptoms are said to be the same for all other variants and sub-variants, such as sore throat, shortness of breath, fatigue, and runny nose.
Sub-variants like XE are common, not necessarily more dangerous
Recombinant strains of coronaviruses, which are mixtures of two strains, are bound to emerge as virus circulates among people, according to experts.
Carlos Malvestutto, an infectious disease specialist at the Ohio State University Wexner Medical Center, told Healthline, “It has already happened a few times and usually the way that it happens is you have two circulating variants, someone may get infected with both at the same time and then the virus will recombine with characteristics of both variants.”
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Malvestutto said there is no indication so far that XE is any better at escaping immunity from either earlier infection or vaccination.
Carl Fichtenbaum, an expert at the Cincinnati College of Medicine, said increased transmissibility of XE – or any other variant of the virus – does not necessarily make it more dangerous.
He said, “It just means that in animal models and humans, the rate of infection is higher. It does not mean it makes you sicker or more likely to be hospitalised.”
