This strain is a mix of two previous Omicron subvariants. A recombinant variant is created when a person is infected with two strains of a virus that then reproduce, resulting in a different strain.
ESR has detected a number of cases of the new strain in clinical samples.
Epidemiologist Michael Baker, a Wellington-based Professor at the University of Otago, said a clear strategy is needed to reduce the impact of XEC.
It has been reported in about 30 other countries, including Australia.
Prof Paul Griffin, from the University of Queensland, told RNZ's Checkpoint programme today XEC seemed to be more infectious than other subvariants.
Although it did not seem to be more severe, Griffin said, it did seem to have "the concerning hallmarks of a subvariant."
"In many parts of the world it's predicted it'll be dominant, perhaps even by the middle of this month."
People needed to maintain a certain level of readiness and mitigating strategies, he said.
"At the moment, I think one of our biggest challenges is actually complacency.
"The fact that we've got a new subvariant that's looking more infectious than taking over in many parts of the world, it should be a reminder that we need to keep up some of those basic strategies like vaccination, antivirals and simple measures to reduce getting infected and onward transmission."
The current Covid-19 vaccine is predicted to still be able to protect from the XCC subvariant too, he said.
"One of the challenges we face is a lot of people are saying that JN1 is not going to protect against XCC because it sounds different but in fact that's not the case and while its ability to protect will be reduced to a degree it'll still be very good.
"That'll be a really important part of our strategy to combat XCC and even the next subvariant that'll inevitably follow it."
