Average daily new COVID-19 cases in the United States approached 400-thousand amid the rapid spread of the omicron variant. 

According to the Washington Post on Sunday, the seven-day average of new daily cases came to 396-thousand-490, a two-fold increase from a week ago. 

The New York Times reported that as of Saturday, the daily average of new infections in the U.S. over the past 14 days reached 386-thousand-920, with the average daily death toll marking one-thousand-240 deaths over the period.

According to the tally by Johns Hopkins University on Sunday, the total number of COVID-19 cases in the U.S. soared to over 55 million, and the nationwide death toll surpassed 825-thousand. 

Top U.S. pandemic advisor Anthony Fauci said on Sunday that the U.S. is experiencing an almost vertical increase in cases as omicron sweeps the country, calling the soaring infection rate "really unprecedented."