The CDC announced this week that the BA.2 Omicron variant, which is reportedly 30% more transmissible than the original BA.1 Omicron strain — has become dominant among new cases sequenced in the United States. That’s a startling rise for a variant that was less than 1% of all sequences as recently as January. But, just as Americans are hearing about BA.2, there’s already a newer, even more transmissible variant on the rise.
There are actually three new variants that have been given designations. According to a recently-released report from the UK Health Services Agency, the two being called XD and XF are combinations of Delta and BA.1, or so-called “Deltacron” strains, which have been talked about for months but made no significant inroads in any country.
Like the other two new arrivals, XE is a recombinant strain, meaning it is made up of two previously-distinct variants. But it is not a Deltacron mix. XE is actually made up of the original Omicron (BA.1) and the newer Omicron (BA.2) which has taken over in the U.S.
The World Health Organization issued a report yesterday with some preliminary findings.
“The XE recombinant was first detected in the United Kingdom on 19 January and >600 sequences have been reported and confirmed since,” reads the WHO document. “Early-day estimates indicate a community growth rate advantage of ~10% as compared to BA.2, however this finding requires further confirmation.”
