What is XEC, the new COVID variant spreading in the West?

A new coronavirus variant is sweeping through Europe and the United States as officials advise ramping up monitoring of its spread.

The variant – known as XEC – has infected 600 people across Europe and North America just ahead of the winter season in the Northern Hemisphere, during which respiratory diseases are typically more widespread.

The variant appears to spread more easily than previous types of COVID but cases of the infection have not been as severe as those seen during the peak years of the pandemic.

So what is different about XEC and is there cause for concern?

XEC is a “recombinant” version of SARS-CoV-2 – the virus that caused the original COVID-19 pandemic.

Recombinants form when a person is infected with two different strains of COVID at the same time. Genetic material from the two different strains then “recombines” or “exchanges” with each other, creating a third, new strain.

While symptoms from XEC have so far been reported as mild, the new strain is part of the “Omicron” lineage – a more severe variant of coronavirus which peaked in 2022.

Each variant or strain develops mutations which are characterised by different “spike proteins” on the virus. These proteins are what bind to human cells, allowing the virus to enter and start replicating inside the human body.

Over time, Omicron has developed its own offshoots or subvariants. Two of these – KP.3.3 and KS.1.1 – are the two which have recombined to form XEC. They are closely related and evolved from the earlier JN.1 variant, which is also part of the Omicron lineage and was dominant around the world in early 2024.