After its detection in 28 countries, the CDC began tracking the proportions of COVID-19 variant XEC.
Currently accounting for 6% of U.S. cases, XEC is the fifth most dominant variant in the nation. Other leading variants include KP.3.1.1 (58.7%), KP.2.3 (9.4%), LB.1 (7.9%) and KP.3 (7.1%).
As of Sept. 19, the XEC lineage has been detected in 633 COVID-19 cases after first appearing June 28, according to Scripps Research's Outbreak.info. Twenty-four states have at least one XEC case. In early September, XEC was seen in 12 states and 15 countries.
It is too early to determine whether the variant is more transmissible or more severe than current strains, experts told NBC News in a Sept. 27 article.
In the week ending Sept. 21, test positivity decreased 1.8%, COVID-19 emergency department visits fell 0.4%, deaths declined 0.2% while hospitalizations fell from 3.6 per 100,000 people to 2.3, according to the CDC's week-to-week comparison.