A variant the World Health Organization and CDC began tracking in mid-July, XBB-offshoot EG.5, became the dominant COVID-19 variant in the first week of August, according to CDC data.
As of Aug. 8, EG.5 accounts for 17.3 percent of COVID-19 cases. Other leading variants include XXB.1.16 with 15.6 percent of infections, XBB.2.3 with 11.2 percent and XBB.1.5 with 10.3 percent.
Some experts have nicknamed EG.5 "Eris," but the WHO has not officially named it.
The variant's prevalence has risen globally since late May, according to the WHO, but there is no evidence linking EG.5 with higher transmission rates or infection severity. The upcoming tweaked boosters will target XBB.1.5 — which was the dominant variant when the FDA advised vaccine-makers in June to alter their formulas — but health experts predict the shots will be effective because XBB.1.5 is mostly similar in mutations.