The World Health Organization is monitoring a new omicron variant — dubbed XE — that’s a hybrid of BA.1, the original omicron strain, and BA.2, a highly transmissible subvariant.
Five things to know:

  1. The strain was identified Jan. 19 in the U.K. As of March 25, authorities had confirmed 637 cases of XE through genetic sequencing.
  2. Initial estimates suggest XE is 10 percent more transmissible than BA.2, though more research is needed to confirm this finding, WHO said.
  3. XE is a recombinant variant, meaning it comprises genetic materials from two distinct virus strains.
    “Recombinant variants are not an unusual occurrence, particularly when there are several variants in circulation, and several have been identified over the course of the pandemic to date,” Dr. Susan Hopkins, chief medical adviser for the U.K. Health Security Agency, said in a March 25 news release.
  4. XE will maintain its omicron variant designation unless further research reveals significant differences in transmission and disease characteristics, including severity, WHO said.
  5. Chinese health authorities also recently identified two new omicron subvariants — one derived from BA.1 and one from BA.2 — that don’t match any existing sequences in China or international databases, according to Bloomberg. Each subvariant was found in just one individual, and it’s still unclear whether the cases are one-off events or more significant findings.