As COVID-19 variant KP.3.1.1 remains the top circulating variant in the U.S., XEC has climbed from the fifth to second most dominant variant, according to CDC data.
For the two weeks ending Sept. 28, KP.3.1.1 accounted for 52.6% of cases, KP.2.3 was 10.4%, LB.1 was 8.3%, KP.3 was 8.1% and XEC was 5.3%.
Over the following two weeks, KP.3.1.1 grew to 57.2% of cases, and XEC jumped to account for 10.7%. The other three declined in prominence: 7.8% of cases were KP.2.3, 5.8% were LB.1 and 5.7% were KP.3.
All five of these variants are offshoots of the JN.1 lineage, which stems from omicron subvariant BA.2.86.
Three other updates:
1. Nationally, the wastewater viral activity level for COVID-19 is low. For the week ending Oct. 5, Montana and Oregon reported very high wastewater viral activity levels, and 14 other states reported high levels.
2. COVID-19 test positivity, emergency department visits, hospitalizations and deaths have continued to decline since mid-August.
3. A CDC spokesperson told USA Today the agency is not seeing any new or unusual symptoms associated with XEC or any other lineage currently circulating. In late September, epidemiology experts told NBC News it was too early to determine whether XEC is more transmissible or more severe than other variants.