COVID-19 variant is expected to surpass KP.3.1.1 as the most dominant circulating variant, according to a preprint study from researchers at universities in Japan and the United Kingdom.
As of Oct. 12, the most recent CDC data available, KP.3.1.1 accounts for 57.2% of COVID-19 cases, followed by XEC (10.7%), KP.2.3 (7.8%), LB.1 (5.8%) and KP.3 (5.7%). Two weeks prior, XEC was fifth with 5.3% of cases.
In the U.S., researchers found the reproduction number of XEC is 1.13-fold higher than that of KP.3.1.1, which has been the most dominant variant since mid-August. In other countries where XEC has spread, including the U.K. and Germany, the variant has also shown a high reproduction number compared to other variants.
"These results suggest that XEC has the potential to outcompete the other major lineage including KP.3.1.1," according to the preprint.
The researchers also assessed virological properties with pseudovirus infection assays, which showed the infectivity of XEC and KP.3.1.1 are significantly higher than KP.3. The XEC variant also revealed higher immune evasion than KP.3.
The CDC began tracking XEC, an offshoot of KP.3, in late September after its detection in 28 countries. Read more from the preprint here.