Omicron sweeps across nation, now 73% of new US COVID casesTravelers wait for a shuttle but to arrive at the Los Angeles International Airport in Los Angeles, Monday, Dec. 20, 2021. (AP Photo/Jae C. Hong)Travelers wait for a shuttle but to arrive at the Los Angeles International Airport in Los Angeles, Monday, Dec. 20, 2021. The national rate suggests that more than 650,000 omicron infections occurred in the U.S. last week. Much about the omicron variant remains unknown , including whether it causes more or less severe illness. On Monday, the CDC revised its estimate for omicron cases for the week that ended Dec. 11, after analyzing more samples.
