Recombinant versions of the coronavirus occur when a single cell is simultaneously infected with two related viruses, as seen in the Omicron XE variant, which is a combination of the BA.1 and BA.2 subvariants of the Omicron variant.
When such recombination of viruses occurs, there is a possibility that the genetic material of the two viruses will mix as they replicate.
But Omicron XE is not the only recombinant variant that has been detected so far, with recombinant variants such as "Deltacron" - a combination of the Omicron and Delta variants - preceding it.
XE is not the only BA.1-BA.2 recombinant variant as well, with a total of 11 such variants that are a mix of their parent viruses, such as XR, XJ and XM.
Delving into the genetic make-up of Omicron XE itself, which experts say is no cause for panic, the recombinant virus has the spike protein and other key features of BA.2, while a smaller portion of its genomic make-up comes from BA.1.
According to public health experts, recombinant variants are a common feature of viruses like the novel coronavirus. While they crop up quite frequently, they usually disappear on their own.
Britain, where Omicron XE was first detected, has said that early research indicates that the variant could be slightly more transmissible than BA.2.
However, the World Health Organisation said that more due diligence is required before XE should be labelled as a variant of concern.
Thus far, there has been no evidence that Omicron XE can evade vaccines, cause more serious illness or increase the risk of death.